Question

notes circumference is the around a circle. c = 2 x 3.14 x r (r = radius) or c = 3.14 x d (d = diameter) ex #1 find the circumference of a circle with a radius of 4.5 cm. c = 2 x 3.14 x 4.5 c = ____ cm ex #2 find the circumference of a circle with a diameter of 1.7 m. c = 3.14 x 1.7 c = ____ m practice 1. find the circumference of each circle below. show work! a) b)

Explanation:

Step1: Recall the circumference formula

For a circle, if the radius $r$ is known, $C = 2\times3.14\times r$; if the diameter $d$ is known, $C=3.14\times d$.

Step2: Solve part a

The diameter $d = 10$ cm. Using the formula $C = 3.14\times d$, we have $C=3.14\times10 = 31.4$ cm.

Step3: Solve part b

The radius $r = 8$ m. Using the formula $C = 2\times3.14\times r$, we get $C=2\times3.14\times8=50.24$ m.

Answer:

a) $31.4$ cm
b) $50.24$ m