Question

The area of a circle is A1 and the area of a regular pentagon inscribed in the circle is A2 . Then A1 : A2 is

(a) π/5 cos π/10

(b) 2π/5 sec π/10

(c) 2π/5 cosec π/10

(d)

Answer 1

Correct option (b) 2π/5 sec π/10

Explanation:

In the Δ OAB,