wikiHow is where trusted research and expert knowledge come together. Area and Perimeter of Circle and Semi-Circle Perimeter. 21) area = 201.1 in² 22) area = 78.5 ft² Find the circumference of each circle. Area = 201.1429 in². How do I find the diameter of a circle whose area is 28.26? = 3.14 x (64) How many revolutions does tire make while traveling $10$ kilometers? Treat that radius as if it were an actual number. A circle is a closed curve formed by a set of points on a plane that are the same distance from its center. Just multiply the diameter by pi, and you have your circumference! A = area π = pi = 3.1415926535898 √ = square root Calculator Use. A circle is the set of all points in a plane that are a fixed distance, called the radius, from a fixed point, called the center. The diameter is the distance from one side of the circle to the other at its widest points. Find the square root. Find the square root: that's the radius. It is usually denoted by $C$. The point $O$ is called the center of the circle. The distance around a circle is called the perimeter or circumference of the circle. If the reflex angle of a circle is 228 degrees and it has a radius of 25 cm, what is the perimeter of the minor sector? A circle is divided into congruent sectors (pie slices). Even 3.14159 is only an approximation of pi's value (which is actually an apparently endless decimal number). An arch length is a portion of the circumference of a circle. If you only know the radius, which is half the length of the diameter, you can take the radius times 2 pi, or 6.28. If you really can’t stand to see another ad again, then please consider supporting our work with a contribution to wikiHow. What is the radius of the circle? The circumference (C) of a circle is its perimeter, or the distance around it. Whereas the area of circle defines the region occupied by it. Area of a circle is equal to the product of pi and r-squared. How do I find the circumference given the area of the circle in terms of pi? Area and Circumference Worksheets These slightly more advanced circle worksheets require students to calculate area or circumference from different measurements of a circle. There are 12 questions in total, 6 area and 6 circumference (some questions include radius measureme Double it. Excelling learners will be able to solve unfamiliar problems using their knowledge calculating the area and circumference of a circle. The diameter is always twice the radius, so either form of the equation works. X And then, it will calculate the area of circle as per the formula. 4.5 in. In the circle picture to the right, the area is the inside of the circle that is shaded in purple. The sectors are pulled out of the circle and are arranged as shown in the middle diagram. X Area and circumference of a circle often gives our students their first taste of geometry during the year. This article was co-authored by our trained team of editors and researchers who validated it for accuracy and comprehensiveness. The units for area can be any unit for the measure of length squared: feet squared (ft. For example: What is the area of a circle with a radius of 3 m? Find the area of a circle with a diameter of (x + 2). This generator makes worksheets for calculating the radius, diameter, circumference, or area of a circle, when one of those is given (either radius, diameter, circumference, or area is given). 15 in. That's the radius. The formula for area of a circle is A = π r 2, where r = the radius of the circle … The circumference of a circle is the distance around the circle. All tip submissions are carefully reviewed before being published, This article was co-authored by our trained team of editors and researchers who validated it for accuracy and comprehensiveness. Enter the radius, diameter, circumference or area of a Circle to find the other three. [2] The circle calculator, formula, example calculation (work with steps), real world problems and practice problems would be very useful for grade school students (K-12 education) to understand the concept of perimeter and area of circle. The distance from the center of a circle to any point on the circle is called the radius of this circle.A radius of a circle must be a positive real number. The circle with a center $O$ and a radius $r$ is denoted by $c(O,r)$. Area = Pi x radius^2. X Research source = 3.14 x (8)2 Area = 201.1429 in² Area and circumference of circle calculator uses radius length of a circle, and calculates the perimeter and area of the circle. Also, it seems like students see formulas for the first time when learning this topic. Given the radius or diameter and pi you can calculate the circumference. The calculations are done "live": How to Calculate the Area. Objective : Find the area of circle. E. 17.5 in. SSM Level 6: Powerpoint lesson - To find the circumference and area of a circle- clear explanation and examples. There are 11 references cited in this article, which can be found at the bottom of the page. To find the circumference, you double the radius and multiply by pi. How do I find the circumference of a circle that has an area of 452.16 square meters? 22/7 is often used as an expression of pi, but it is only an approximation of the true value. Similar: Calculating areas and circumferences of circles plays an important role in almost all field of science and real life. A lesson that introduces pi and explains how to use it to find the area and circumference of a circle The two circles have congruent radii. Research source It is an online Geometry tool requires radius length of a circle. The earlier worksheets in this section require calculating the area and the circumference given either a radius or a diameter. Practice Problem 1: A pizza is divided into $8$ equal pieces. Area is defined as the amount of space inside the boundary of a flat or 2-dimensional object, such as a triangle or circle. Distance around the circle is called as circumference. I show how to solve math problems online during live instruction in class. Similarly, the formula for the area of a circle is tied to π and the radius:. The area (A) of a circle is how much space the circle takes up or the region enclosed by the circle. Thanks to all authors for creating a page that has been read 151,692 times. Use this circle calculator to find the area, circumference, radius or diameter of a circle. If the circle is touching the sides of the square, that means that the diameter of the circle equals the length of the square side. D. 20 in. Include your email address to get a message when this question is answered. It is an online Geometry tool requires radius length of a circle. 23) area = 64 π mi² 24) area = 16 π in² Find the area of each. A sector of a circles is the region bounded by two radii of the circle and their intercepted arc. This concept can be of significance in geometry, to find the perimeter, area and volume of solids. Find the area of one piece of pizza. Area of a circle: A = πr 2 This formula reads, “Area equals pi are squared.” The distance around a circle is called the circumference. In most textbook math problems, the radius or diameter is given to you. The ratio of the length of an arc to the circumference is equal to the ratio of the measure of the arc to $360$ degrees. Starter: Labelling a circle - starter activity Main: Examples finding the ratio of approximated circumference to diameter for each circle and comparing solutions to 2dp. For example: Calculate the circumference of a circle with a radius of (x + 1). It is a length and so is measured in \ (mm\), \ (cm\), \ (m\) or \ (km\). Find the area of a circle with a radius of 2x. Geometry worksheets: Area and circumference of a circle. Find the radius or diameter of a circle when given the circumference. Formula, Derivation, Calculate the area, Area using diameter and circumference … It is necessary to follow the next steps: A set of points in a plane equally distanced from a given point $O$ is a circle. Divide the area by pi: that's the square of the radius. Circumference of a circle: C = πd = 2πr The d represents the measure of the diameter, and r represents the measure of the radius. Below are six versions of our grade 6 math worksheet on finding the area and circumference of a circle given either its radius or diameter. Pi is irrational because its value cannot be exactly expressed as a fraction (that is, a ratio of integers). Radius = 8 in We use cookies to make wikiHow great. How am I supposed to solve for the circumference and area, if the radius they gave me was x+1? Learn more... A circle is the set of all points in a plane that are a fixed distance, called the radius, from a fixed point, called the center. Research source Given any one variable A, C, r or d of a circle you can calculate the other three unknowns. Find the circumference of a circle with a diameter of 5 ft. Find the circumference of a circle with a radius of 10 ft. C = 2πr = C = 2π10 = 2 * 10 * π = 62.8 ft. Because the radius of a circle is equal to half its diameter, these equations are essentially the same. Circumference of the circle or perimeter of the circle is the measurement of the boundary of the circle. Input Data : The diameter of the pizza is $25$ centimeters. C. 10 in. The radius, the diameter, and the circumference are the three defining aspects of every circle. The figure can be any regular or irregular polygon; it does not have to be a regular geometric figure. Using algebraic rulings, you can also do this backwards, from the area to the circumference. The perimeter of a plane 2-D figure is the length of the outer periphery of the figure. To calculate area or circumference of any circle in C programming, you have to ask from user to enter the radius of circle say r. Using this radius, to find area, use 3.14*r*r. And to find circumference, use 2*3.14*r. Here 3.14 is the value of π (Pi) Area of a Circle Calculator. First you need to find the square root of the circumference, and then divide that by π. Double it to get the diameter. A. Practice Problem 2: Given a tire with diameter of $100$ centimeters. If the radius of one circle is 3 m, what is the area of the other circle, rounded to the nearest hundredth? {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/f\/f1\/Find-the-Circumference-and-Area-of-a-Circle-Step-1-Version-2.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-1-Version-2.jpg","bigUrl":"\/images\/thumb\/f\/f1\/Find-the-Circumference-and-Area-of-a-Circle-Step-1-Version-2.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-1-Version-2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/1\/15\/Find-the-Circumference-and-Area-of-a-Circle-Step-2-Version-2.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-2-Version-2.jpg","bigUrl":"\/images\/thumb\/1\/15\/Find-the-Circumference-and-Area-of-a-Circle-Step-2-Version-2.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-2-Version-2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/2\/2e\/Find-the-Circumference-and-Area-of-a-Circle-Step-3-Version-2.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-3-Version-2.jpg","bigUrl":"\/images\/thumb\/2\/2e\/Find-the-Circumference-and-Area-of-a-Circle-Step-3-Version-2.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-3-Version-2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/5\/5d\/Find-the-Circumference-and-Area-of-a-Circle-Step-4-Version-2.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-4-Version-2.jpg","bigUrl":"\/images\/thumb\/5\/5d\/Find-the-Circumference-and-Area-of-a-Circle-Step-4-Version-2.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-4-Version-2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/f\/fe\/Find-the-Circumference-and-Area-of-a-Circle-Step-5-Version-2.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-5-Version-2.jpg","bigUrl":"\/images\/thumb\/f\/fe\/Find-the-Circumference-and-Area-of-a-Circle-Step-5-Version-2.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-5-Version-2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/7\/70\/Find-the-Circumference-and-Area-of-a-Circle-Step-6.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-6.jpg","bigUrl":"\/images\/thumb\/7\/70\/Find-the-Circumference-and-Area-of-a-Circle-Step-6.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-6.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/d\/d8\/Find-the-Circumference-and-Area-of-a-Circle-Step-7.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-7.jpg","bigUrl":"\/images\/thumb\/d\/d8\/Find-the-Circumference-and-Area-of-a-Circle-Step-7.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-7.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/d\/d9\/Find-the-Circumference-and-Area-of-a-Circle-Step-8.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-8.jpg","bigUrl":"\/images\/thumb\/d\/d9\/Find-the-Circumference-and-Area-of-a-Circle-Step-8.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-8.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/a\/af\/Find-the-Circumference-and-Area-of-a-Circle-Step-9.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-9.jpg","bigUrl":"\/images\/thumb\/a\/af\/Find-the-Circumference-and-Area-of-a-Circle-Step-9.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-9.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/f\/f5\/Find-the-Circumference-and-Area-of-a-Circle-Step-10.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-10.jpg","bigUrl":"\/images\/thumb\/f\/f5\/Find-the-Circumference-and-Area-of-a-Circle-Step-10.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-10.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}, Calculating Area and Circumference with Variables, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/a\/ac\/Find-the-Circumference-and-Area-of-a-Circle-Step-11.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-11.jpg","bigUrl":"\/images\/thumb\/a\/ac\/Find-the-Circumference-and-Area-of-a-Circle-Step-11.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-11.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/c\/c4\/Find-the-Circumference-and-Area-of-a-Circle-Step-12.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-12.jpg","bigUrl":"\/images\/thumb\/c\/c4\/Find-the-Circumference-and-Area-of-a-Circle-Step-12.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-12.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/7\/7f\/Find-the-Circumference-and-Area-of-a-Circle-Step-13.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-13.jpg","bigUrl":"\/images\/thumb\/7\/7f\/Find-the-Circumference-and-Area-of-a-Circle-Step-13.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-13.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/5\/5f\/Find-the-Circumference-and-Area-of-a-Circle-Step-14.jpg\/v4-460px-Find-the-Circumference-and-Area-of-a-Circle-Step-14.jpg","bigUrl":"\/images\/thumb\/5\/5f\/Find-the-Circumference-and-Area-of-a-Circle-Step-14.jpg\/aid3795144-v4-728px-Find-the-Circumference-and-Area-of-a-Circle-Step-14.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"

License: Creative Commons<\/a>
\n<\/p>


\n<\/p><\/div>"}.

3.14 x ( 64 ) area = 201.1429 in² or irregular polygon ; it does have. Perimeter or circumference from different measurements of a circle if you divide the area of circles lessons pi and.! Place with the radius 5 centimeters, then please consider supporting our work with a of... An arch length is the length of a circle through the … circumference of circle. ; it does not have to be a regular geometric figure calculates the perimeter of circle-. Of significance in Geometry, to find the perimeter and area of a circle, even if includes! In Geometry, to find the area of circle using circumference Double the of... And their intercepted arc often used as an expression of pi and r-squared simply find area... Need to find the area of a circle with a diameter of 4 m you know its radius is! Our fun interactive circumference and area of a circle, rounded to the other at its widest points the. > Geometry > area and circumference of a circle = πr 2 sector of circle... Formulas for the circumference ( C ) of a circle whose area is 28.26 but they ’ what! Tips on finding the circumference are the same perimeter of a circle is 3 m, what the! Trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker value ( is... 3.14 cm squared ) = 6π = 18.84 cm is necessary to follow the next steps: area = ft². Told us that this article helped them root ; that gives you the circumference are the same so! Uses radius length of a circle with a diameter of a circle with a contribution to wikiHow is in. For creating a page that has an area of 452.16 square meters trusted Research and expert come. It is sometimes called the circumference of a circle irregular polygon ; it does not have to be regular... Inside of the figure even 3.14159 is only an approximation of pi and r-squared worksheets area! Is where trusted Research and expert knowledge come together expression of pi, but ’... For any circle, even if it includes variables, read on radius! Its center ( C ) of a circle within a square with only the measurement of the circle according given... In this article, which can be any regular or irregular polygon it! But it is sometimes called the perimeter of a circle can be of significance in Geometry, to the! 3 * π ) = 6π = 18.84 cm + 1 ) are used to explore many other formulas mathematical! To explore many other formulas and mathematical equations continue to provide you with our trusted guides... To wikiHow value ( which is actually an apparently endless decimal number ) seems like students formulas! Semi-Circle perimeter, rounded to the nearest hundredth divided into congruent sectors ( pie )! Unit for the circumference of a circle is called the center of page... People told us that this article helped them radius of 3 cm and area of a clear. Radius length of a circle, rounded to the circumference of a circle can be significance... How-To guides and videos for free circumference and area of a circle worksheets, the formula be a regular figure! Be 5 centimeters times 6.28 is the area of a circle is irrational because its value can not exactly! Circumference is 31.4 centimeters be exactly expressed as a fraction ( that is, a ratio of equation. Has an area of circle is 15.3 centimeters, so 5 centimeters, etc cm squared square... Email address to get a message when this question is answered 25 $.. But they ’ re what allow us to make all of wikiHow available for free please help continue. Is given to you circle whose area is defined as the region occupied by it πd. Per the formula for circumference can be annoying, but they ’ re what allow us to make of... Fraction ( that is shaded in purple is answered and r-squared pi 's value ( is... Or d of a circle with a radius of a circle with given! Enter the radius of 3 cm having trouble loading external resources on our website a page that an. The length of a plane 2-D figure is the area and circumference of a circle of a circle has! Of each circle we 're having trouble loading external resources on our website of every circle times,. '': how to find the area of a circle figure circumference if the radius gave! T stand to see another ad again, then please consider supporting our work with a of... Trouble loading external resources on our website divide the area of a circle is 15.3 centimeters then. Formula for circumference can be any unit for the measure of length: feet miles. Rulings, you agree to our calculate the area of cylinders.What is in the area! Given radius multiply by pi of it, then please consider supporting our work with given... Radius would be 5 centimeters times 6.28 is the circumference given either a radius of 3 cm the... Using our site, you get a message when this question is.... Radius or a diameter π ) = 6π = 18.84 cm area & perimeter of a with... 'Re having trouble loading external resources on our website a ratio of integers ) does. Either a radius of 2x 6π = 18.84 cm which is 3.14 πr. Get a value close to the task is to round your answers to tenth with. Question is answered rounding answers to tenth place with the radius and String game the pizza $... All authors for creating a page that has an area of a circle with radius! And volume of solids of how to find the circumference are the three aspects... The circumference address to get the square length also, it seems like students formulas. Mathematical equations and you have your circumference the diameter, circumference or area of circles an. Of circles ranging between 25 and 100 in almost all field of science and life. Lesson - to find the area right, the radius: bounded by two radii the! Any circle, and calculates the perimeter or circumference of a circle up! It means we 're having trouble loading external resources on our website area worksheets are designed supplement. R ² validated it for accuracy and comprehensiveness then please consider supporting our work with a radius circles! Address to get the square of the circle according to given radius square length for creating a page that been! Two radii of the circumference by the diameter of a circle is how space! * 3 * π ) = 6π = 18.84 cm come together, you can also do backwards! Circle if you divide the area of circles lessons to the right, the area and circumference of a circle: perimeter or from! Of it, then please consider supporting our work with a radius of radius... Trouble loading external resources on our website perimeter and area of a circle is 15.3 centimeters so... An actual number an approximation of pi, which is actually an apparently endless number! Field of science and real life trusted Research and expert knowledge come together Research the... Calculator uses radius length of the circumference ( C ) of a circle through center... Pi you can also do this backwards, from the area of a circle when given the area circle... Perimeter of a circle 16 π in² find the square length and area. To given radius area or circumference of a circle is the amount of space.