Question

If the circumference of a circle exceeds its diameter by $30$ cm, find the radius of the circle.

Answer 1

We know, that,

Circumference of a circle $=2\pi r$

According to the question,

$\Rightarrow 2\pi r=2r+30$

$\Rightarrow 2\pi r-2r=30$

$\Rightarrow 2r(\frac{22}{7}-1)=30$

$\Rightarrow 2r\left(\frac{22-7}{7}\right)=30$

$\Rightarrow r=\frac{30\left(7\right)}{2\left(15\right)}=7$ cm