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 nearest hundredth centimeters. (Take $\pi =\frac{22}{7}$)

Answer 1

When two sectors of ${90}^{\circ }$ are removed, we will be left with the shaded portion as shown below:

It's perimeter $=\pi r+4r=\frac{22}{7}\times 3+4\times 3$

$=9.428+12=21.428cm$