Question

If two circles have their diameters in the ratio $1:2$ what will be the ratio of their cicumferences?

Answer 1

$\to$ As circumference of

circle of radius r $=2\pi r$

And as radius $=\frac{diameter}{2}$

$\Rightarrow$ circumference = $\pi d$

$\Rightarrow \frac{\pi d_1}{\pi d_2}=\frac{d_1}{d_2}=\frac{1}{2}=1:2$