Question

Raj cuts a disc with a radius of 7 cm into two equal parts. Calculate the entire perimeter.

• A. 32 cm
• B. 35 cm
• C. 36 cm
• D. 42 cm

Answer 1

The correct option is C 36 cm

When the circular disc is divided into two equal parts, we get two semi-circular discs.

Now, the perimeter of each semi-circular disc thus obtained is given by

$\frac{1}{2}\times$ Perimeter of the circle + Diameter

[Since diameter of the circle will also be a part of the semi-circular disc]

Perimeter of the semi-circle

$=\frac{1}{2}\times 2\pi r+2r$
$=\pi r+2r=r(\pi +2)$
$=7\times (\frac{22}{7}+2)$
$=36cm$

Therefore, perimeter of each semi-circular disc is 36 cm.