If the area of a semi-circle be 77 sq m, find its perimeter.

According to the question,
Area of semi- circle = 77 m
(1/2) x π x r² = 77
⇒ r² = (77 x 2 x 7)/22
∴ r = 7m
∴Circumference of semi- circle =πr + 2r
= ( π + 2)r
= [(22/7) + 2] x 7
= 36 m