how to find area of a circle

Grace is currently a math instructor at the City College of San Francisco and was previously in the Math Department at Saint Louis University. Make sure you know if you are measuring the small angle between the two radii or the greater angle outside them. Convert the area of a circle into an rectangle shaped area of the same size. She has an MA in Education, specializing in Administration and Supervision from Saint Louis University. ", "I was doing homework and got stuck on something. Then, you would multiply 36 by π and get 113.04. Circle I found this and finished really quickly! You need to know the formula for finding the area of a circle, A=πr2{\displaystyle A=\pi r^{2}}. (If you're asking how to convert from square inches to square feet, divide the number of square inches by 144 to get square feet.). Enter 4 ft in the diameter box. In some problems, instead of having you measure the central angle, the problem may just tell you the measurement. ", "I was looking for different ways to find the area of a circle and this really helped!!! Finally, you would divide 1,764 by 12.57 and get 140.4. ", "Math has never been my strong point. ", "Small business, estimating the cost of a product that is a circle. ", "Thx for this article. The area of a circle is pi times the radius squared (A = π r²). ", but after this, I don't just know it, I understand it! D in the formula refers to the diameter which is the width of the circle. Please go through following articles of c programming, if you do not already know about these topics : Divide the area in square centimeters by 10,000 to find the area in square meters. Ten squared is 100, and 100 times π is 314.16. The formula for the area of a circle is A = pi * r * r where r is the radius (diameter / 2). ", "This article will help me pass the math exams for getting a score in school. Now let's move on to the program. Find Area of Circle To calculate area of any circle in C++ programming, you have to ask from user to enter the radius of circle, place the radius in a variable say rad and then initialize 3.14*rad*rad in a variable that holds the value of area of circle, as shown here in the following program. We use cookies to make wikiHow great. You can find the area of a circle using the radius, the diameter, or the circumference. To find the circumference of a circle, simply multiply the diameter by pi (3.14). Find the area of a circle given its radius, diameter, or circumference. Label the radius and notice that the diameter of the circle is equal in length to the side of the big square. Knowing for sure requires seeing a cross section. you have five copies of an isosceles triangle and you know all the side lengths, so you should be able to find the area of the triangle and therefore, the whole pentagon. Grace Imson is a math teacher with over 40 years of teaching experience. For example, if the radius of the circle is 6 inches, first you would square 6 and get 36. If you don't know the radius, however, you can still calculate the If you want to find the area of a sector from a circle, keep reading the article! Find the radius of the circle. By using this service, some information may be shared with YouTube. You can also provide the numerical approximation by multiplying by 3.14 instead of. I know the circumference of an object, how do I find the area? Do not get confused and square the entire equation. We know ads can be annoying, but they’re what allow us to make all of wikiHow available for free. Find a pipe of the same material and exterior dimensions, and measure its interior. How to find the area of a circle: The area of a circle can be found by multiplying pi ( π = 3.14) by the square of the radius If a circle has a radius of 4, its area is 3.14*4*4=50.24 If you know the diameter, the radius is 1/2 as large. It can be difficult to measure to the exact center of a circle, unless the center is already marked for you on a circle drawn on paper. Visual on the figure below: Area Of A Circle Formula If you know the radius, r r, in whatever measurement units (mm, cm, m, inches, feet, and so on), use the formula π r 2 to find area, A A: A = πr2 A = π r 2 The answer will be square units of the linear units, such as mm2 m m … Area of a quarter circle when radius is given calculator uses Area=(pi*(Radius)^2)/4 to calculate the Area, The area of a quarter circle when the radius is given is the area enclosed by a quarter circle of radius r. By signing up you are agreeing to receive emails according to our privacy policy. How do I calculate the circumference of a circle? ", https://www.mathsisfun.com/geometry/circle-area.html, http://www.livescience.com/29197-what-is-pi.html, http://mathcentral.uregina.ca/QQ/database/QQ.09.06/s/amanda4.html, http://www.mathopenref.com/arcsectorarea.html, वृत्त के क्षेत्रफल की गणना करें (Kaise, Calculate, Area of a Circle), consider supporting our work with a contribution to wikiHow. How do I find the total area of five circles joined together? 8 years and grades of suffering in equations and fractions, and still today I, "Knowing more ways than 1 to calculate the area of a circle is helpful. In this example, you will learn about C++ program to find area of the circle with and without using the function. Also, know how to calculate the segment of a circle using examples with its types and theorems here. Therefore, the area of the circle is 140.4 square inches. The diameter of a circle calculator uses the following equation: Area of a circle = π * (d/2) 2 Where: π is approximately equal to 3.14. Therefore, the area of the circle is 314.16 inches squared. Half the diameter is the radius. Thank you so much! How to Calculate the Area of a Circle (with Pictures) - wikiHow For this example, assume that you have been told or have measured that the circumference of a circle (or circular object) is 42 cm. Example 2: A chord AB of a circle of radius 10 cm makes a right angle at the centre of the circle. To find the circumference, C C, (perimeter) of the area of a circle, A A, you apply the formula: C = 2√(πA) C = 2 (π A) Here is a circle with an area of 1,000 km2 1,000 k m 2. It can be determined easily using a formula, A = πr2, (Pi r-squared) where r is the radius of the circle. Square the radius and multiply by pi to find the area. ", "It is my exam math exam and i forgot to ask my teacher about how to find a circle's area, this helped me so much! For example, if the diameter is 20 inches, you would divide that in half and get 10 inches. Find the area of major and minor segments (Take π = 3.14) Sol. C = pi * d calculates the circumference (distance around the outside of the circle). References. I'm also glad I could download the images. Include your email address to get a message when this question is answered. To find the area using the radius, or the length from the center of the circle to the edge, use the formula area = πr^2, where r is the radius. The formula is simple and only needs the radius of the circle to find its area. This article was co-authored by Grace Imson, MA. Draw a perpendicular from the center of the circle to the third side of the triangle and use the sine and cosine of 72/2 = 36 degrees. A common problem in geometry class is to have you calculate the area of a circle based on provided information. So Max should order 0.126 cubic meters of concrete to fill each hole. It is interesting to compare the area of a circle to a square: A circle has about 80% of the area of a similar-width square. She has taught math at the elementary, middle, high school, and college levels. Grace is currently a math instructor at the City College of San Francisco and was previously in the Math Department at Saint Louis University. \ (\pi r^2\) means \ (\pi \times r \times r\). Half the diameter is the radius. :)", "I was studying for a test on circles, now I know how to find out the area of a circle! Here PI value is fixed which is 22/7 or 3.1415926535, but for this problem, we are using a PI value up to 5 decimal digits, If you want to know more about PI click here. Area of a circle = r² Remember that we find the square of … Area of Circle = πr2 or πd2/4, (square unit) where π = 22/7 or 3.14 I was able to finish my assignment. Question: Can you find the area of quadrant of a circle whose circumference is 22? It doesn't matter whether you want to find the However, you need to change the formula so that you square the 'd' otherwise your answer will be wrong. It is very good and has perfect answers. We can plug in our known area into the formula and work from the inside out. wikiHow helps with its clear instructions and explanations, even on depressing afternoons where nothing math-related seems to be going right. Grace Imson is a math teacher with over 40 years of teaching experience. % of people told us that this article helped them. To approximate the area of the circle, we will do the following: 1) Get area of the big square 2) Get the area of the small square If you want to report a numerical value, you can multiply 120 x 3.14 to get a value of 376.8 cm. How to Find the Area of a Circle Using Its Circumference. or, when you know the Circumference: A = C2 / 4π. ", "I love that it shows you different ways. Note: Max could have estimated the area by: 2. Only the \ (r\) is squared. Let’s calculate the are Just type into the box and your conversion will area of circle (A) = πr2 putting the value of r in the above formula, A = 3.14 * (10*10) A = 3.14 * 100 How do I find the area if I was only given the diameter? What do I do if I have a fraction for the radius and want to solve the area of a circle? Then, you would multiply 4 by π and get 12.57. How do I convert inches to feet when finding the area of a circle? I suspect that your problem includes the radius of a chick and the radius of the round box. How can I calculate the number of chicks in a round box? Works much the same way as a circle to square conversion but you will have to enter the width of the rectangle in addition to the circle's diameter. If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked. The formula for working out the area of a circle is: \ (A = \pi r^2\), where \ (r\) is the radius of the circle. Answer: First, find the radius of the circle by dividing the circumfernece by Pi and halving the answer to give 3.501 to 3 decimal places. Taking 80% of that (estimates a circle). This article has been viewed 5,223,618 times. (even though pies are usually round). The actual value is (π/4) = 0.785398... = 78.5398...%, Why? Because the Square's Area is w2 You convert inches to feet the same way to find the area of a circle as you do to find anything else. Can you see the next step? Standard formula to calculate the area of a circle is: A=πr². See Circle Area by Lines Names Because people have studied circles for thousands of years special names have come about. Area of a circle = π * r 2 Area of a circle diameter. Thanks to all authors for creating a page that has been read 5,223,618 times. She has taught math at the elementary, middle, high school, and college levels. How do I get the inside dimensions of a pipe with a total length of 45 inches? You wouldn't be asking, I presume, if you could see the inside. ", "I only had a slim clue on how to calculate the area of a circle, and this helped me fully understand. To find the area of the quarter circle, take the area of the whole circle and then divide by 4. Please help us continue to provide you with our trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker. For this sample circle, with a circumference given as 42 cm, the area is. ", "This is so helpful, I feel I can go and master my exam. It supports different units such as meters, feet, and inches. If the object is a circle, and you know its circumference, you would divide the circumference by pi to find the diameter of the circle. How to write python program to find area of circle using radius, circumstance and diameter If we know the The most common error when using diameter is forgetting to square the denominator. ", "It works well, I'll be using this again.". Plug in 2 for r in the area of a circle formula and solve. If you want to find the area of a sector from a circle, keep reading the article! The segment of a circle and segment of a circle formula in terms of radians and degrees is given here. Math Instructor, City College of San Francisco. For the given example with a radius of 6 cm, the area is calculated as: For the sample circle with a radius of 6 cm, the area will be either 36. I have a final exam tomorrow, wish me luck! She has an MA in Education, specializing in Administration and Supervision from Saint Louis University. Then, plug the radius into the formula for finding area, area = πr^2. The sum of the small angle and the great angle will be 360 degrees. The holes are circular (in cross section) because they are drilled out using an auger. Solution: Let the radius of the circle be r cm. Whenever I do not know something, I always come to this website! find myself struggling. You can find the PI value up to 1,00,000 Decimal Digits. To compute it, we need to know the radius. The unit of area is the square unit, such as m2, cm2, etc. Measure the outside circumference of the pipe, or the outside diameter using something like calipers. = 5 m Summary: Given the radius or diameter of a circle, we can find its area. "Thank you very much for this amazing page and for everything. ", "It really helped. Last Updated: December 27, 2020 How to use a formula to find the area of any circle, How to Find the Area of a Circle, Given a Radius or a Diameter, Grade 6 Related Topics: More Lessons for Grade 6 Math Worksheets Examples, videos, worksheets, stories, and ", "Very good and detailed, helps me understand what school doesn't teach and finish a subject. For example: If d= 23cm, C= 3.14 x 23cm, so C= 72.22cm. The problem you are working on should define this for you. ", "I think this really helped me. Area of a Circle Segment Given the Central Angle Definition: The number of square units it takes to fill a segment of a circle Try this Drag one of the orange dots that define the endpoints of … Therefore, the area of the circle is 113.04 inches squared. Thanks loads! For example, if the circumference is 42 inches, first you would square 42 and get 1,764. By using our site, you agree to our. A = π2 2 A = 4π If you don't divide the diameter by 2 to find the radius, you can still find the area of the circle. If the pipe was made after WWII, try a comparison. How to Calculate Area of a quarter circle when radius is given? Let's figure out how to find an area of a semicircular object - a rug which would fit perfectly in front of your fireplace: Input the diameter or radius of the rug. or, when you know the Diameter: A = (π /4) × D2. If you really can’t stand to see another ad again, then please consider supporting our work with a contribution to wikiHow. This article has been viewed 5,223,618 times. If we know the diameter or circumference and the Circle's Area is (π/4) × w2, Estimate of Circle's Area = 80% of Square's Area = 80% of 9 = 7.2 m2, Circle's True Area = (π/4) × D2 = (π/4) × 32 = 7.07 m2 (to 2 decimals), The estimate of 7.2 m2 is not far off 7.07 m2. The area of a circle is: π ( Pi) times the Radius squared: A = π r2. Area of a circle formula. Since the diameter of the circle is 4 meters, its radius is 2 meters. Assume that our fireplace is 4 ft wide, so we'd like to have the same rug length. ", "It was perfect, and I understood the process! For example, you might be told, “The central angle of the sector is 45 degrees” or you may be expected to measure it. This article was co-authored by Grace Imson, MA. Assume for this example that the diameter of your circle is 20 inches. Most basically, you will need to find the areas of each circle separately, and then add them up. Area of a circle is the region occupied by the circle in a two-dimensional plane. The Formula for Area of Circle Area of a Circle = πr2 or PI * Radius * Radius. However, you also need to practice converting some other bits of provided data into terms that can help you use this formula. The area of a circle is calculated by finding the square of the radius and multiplying this result by . In this article, we will illustrate c program to calculate area of circle.The formula for the area of the circle is : Area_circle = Π * r * r where, mathematical value of Π is 3.14159. You will need to know some more data about the size of a chick and the size of the round box. This free area calculator determines the area of a number of common shapes using both metric units and US customary units of length, including rectangle, triangle, trapezoid, circle, sector, ellipse, and parallelogram. The Area of A Segment of A Circle The Area of A Sector of A Circle Example 2: The circumference of a circle exceeds the diameter by 16.8 cm. For this example, assume that you are told that the radius of a given circle is 6 cm. Calculate the areas, and divide the total area of the box by the area taken up by one chick. The calculations are done "live": To help you remember think "Pie Are Squared" Learn how to use this formula to find the area of a circle when given the diameter. {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/6\/65\/Calculate-the-Area-of-a-Circle-Step-1-Version-6.jpg\/v4-460px-Calculate-the-Area-of-a-Circle-Step-1-Version-6.jpg","bigUrl":"\/images\/thumb\/6\/65\/Calculate-the-Area-of-a-Circle-Step-1-Version-6.jpg\/aid53808-v4-728px-Calculate-the-Area-of-a-Circle-Step-1-Version-6.jpg","smallWidth":460,"smallHeight":345,"bigWidth":728,"bigHeight":546,"licensing":"