Question

1. radius = 5.2 ft 32.7 ft
2. radius = 11 ft 69.1 ft
3. radius = 9.5 in 59.7 in
4. radius = 9.3 in 58.4 in

find the radius of each circle. use your calculators value of π. round your answer to the nearest tenth.

1. circumference = 62.8 mi 10 mi
2. circumference = 69.1 yd 11 yd
3. circumference = 12.6 yd 2 yd
4. circumference = 25.1 ft 4 ft

find the diameter of each circle. use your calculators value of π. round your answer to the nearest tenth.

1. area = 201.1 in² 16 in
2. area = 78.5 ft² 10 ft

find the circumference of each circle.

1. area = 64π mi² 16π mi
2. area = 16π in² 8π in

find the area of each.

1. circumference = 6π yd 9π yd²
2. circumference = 22π in 121π in²

critical thinking question:

1. find the radius of a circle so that its area and circumference have the same value.

r = 2
create your own worksheets like this one with infinite geometry. free trial available at kutasoftware

Explanation:

Step1: Recall circle - area and circumference formulas

The area of a circle is $A=\pi r^{2}$, and the circumference is $C = 2\pi r$.

Step2: Set area equal to circumference

We want $A = C$, so $\pi r^{2}=2\pi r$.

Step3: Solve the equation for r

First, move all terms to one - side: $\pi r^{2}-2\pi r = 0$. Factor out $\pi r$: $\pi r(r - 2)=0$.
Since $\pi
eq0$, we have two solutions from the zero - product property: $r = 0$ or $r-2=0$. But a circle with $r = 0$ is a degenerate case. So, when $r - 2=0$, $r = 2$.

Answer:

$r = 2$