![2.5 inch circle actual size 2.5 inch circle actual size](https://static.primecp.com/master_images/4-in-circle-template.jpg)
You can break it down into a rectangle and a semicircle, as shown below. The first step is to identify simpler figures within this composite figure. The trick to figuring out these types of problems is to identify shapes (and parts of shapes) within the composite figure, calculate their individual dimensions, and then add them together.įor example, look at the image below. Now that you know how to calculate the circumference and area of a circle, you can use this knowledge to find the perimeter and area of composite figures. If you know the diameter ( d) of a circle:
![2.5 inch circle actual size 2.5 inch circle actual size](http://www.clipartbest.com/cliparts/RiG/Exe/RiGExeA9T.jpg)
To find the circumference ( C) of a circle, use one of the following formulas: Since you know that the ratio of circumference to diameter (or ) is consistent for all circles, you can use this number to find the circumference of a circle if you know its diameter.Īlso, since d = 2 r, then C = d = (2r) = 2 r. Note that both 3.14 and are approximations of, and are used in calculations where it is not important to be precise. The first 10 digits of are 3.141592653 it is often rounded to 3.14 or estimated as the fraction. Is a non-terminating, non-repeating decimal, so it is impossible to write it out completely. The mathematical name for the ratio is pi, and is represented by the Greek letter.
![2.5 inch circle actual size 2.5 inch circle actual size](https://i.etsystatic.com/22683753/r/il/21945c/2636553730/il_1588xN.2636553730_4a7o.jpg)
If you were able to measure them more precisely, however, you would find that the ratio would move towards 3.14 for each of the items given. The circumference and the diameter are approximate measurements, since there is no precise way to measure these dimensions exactly. Circumference ( C) (rounded to nearest hundredth)