# How do you find the radius, diameter and circumference of a circle with an area of 64 cm2?

Jun 9, 2018

$A = 64 c {m}^{2}$

$r \approx 4.51 c m$

$d \approx 9.03 c m$

$C \approx 28.36 c m$

#### Explanation:

First let's find the radius $r$ then we can solve the other questions:

Area formula:

${A}_{\text{circle}} = \pi {r}^{2}$

$\frac{A}{\pi} = {r}^{2}$

$\pm \sqrt{\frac{A}{\pi}} = \sqrt{{r}^{2}}$

we can ignore the negative solution because a radius can't be negative in length:

$r = \sqrt{\frac{A}{\pi}} = \sqrt{\frac{64}{\pi}} \approx 4.51$

Diameter formula:

$d = 2 r = 2 \sqrt{\frac{64}{\pi}} \approx 9.03$

Circumference formula:

${C}_{\text{circle}} = 2 \pi r$

$C = 2 \pi \sqrt{\frac{64}{\pi}} \approx 28.36$