Question

Puja decides to cut a circular disc into 4 equal parts. What is the perimeter of each part? (Given that the radius of the disc = 7cm, $\pi$​ = $\frac{22}{7}$)

Answer 1

When a circular disc is cut into four equal parts, the perimeter of each part is more than $\frac{2\pi r}{4}$. This is because the length of two radii are also added to the perimeter in each part.

Perimeter of each part = $\frac{2\pi r}{4}$+ r + r (1 mark)

= $\frac{\pi r}{2}$ + 2r

= $\frac{22\times 7}{7\times 2}$ + 2r

= $11+2\times$7

= 11 + 14

= 25 cm (1 mark)