Question

From a circular piece of cardboard of radius $3$ cm two sectors of ${90}^{\circ }$ have been cut off. Find the perimeter of the remaining portion narest $100$th centimeters. (Take $\pi =\frac{22}{7}$)

Answer 1

Given radius$=3cm$

Two sector of ${90}^o$ cut out $({90}^o\times 2={180}^o)$ means semicircle.

$\Rightarrow$ Perimeter of remaining circle(semicircle)$=\pi r$

$\Rightarrow$ Perimeter of remaining circle(semicircle)$=\frac{22}{7}\times 3$

$\Rightarrow$ Perimeter of remaining circle(semicircle)$=9.428cm$