Question

A sector of a circle as shown in the figure, with angle at the centre equal to 120° has been cut from a circular lamina of radius 21 CM. show that the perimeter of the remaining portion of the lamina is 130 cm .

(solve the sum step by step)​

Answer 1

Answer/Step-by-step explanation:

Perimeter of the remaining sector = length of arc + 2×radius

= θ/360 × 2πr + 2r

θ = 360° - 120° = 240°

r = 21 cm

Plug in the values

Perimeter of the remaining sector = 240/360 × 2×π×21 + 2(21)

= 129.964594 ≈ 130 cm

Therefore, the perimeter of the remaining portion is 130 cm