Question

The circumference of circle of area $64\pi$ square units is

• A. $8\pi$
• B. $16\pi$
• C. $32\pi$
• D. $64\pi$

Answer 1

Answer: (B)

$16\pi$

Area of the circle $=$ $\pi r^2$
Area of the circle $=$ $64\pi$
$\Rightarrow 64\pi =\pi r^2$
$\Rightarrow r^2=64$

$\Rightarrow r=8$
Circumference of the circle $=$ $2\pi r$
$=$ $2\pi \times 8$
$=$ $16\pi$