Question #9db31

1 Answer
Jul 31, 2017

theta = pi/2 , 7pi/6 , 11pi/6

Explanation:

First let x = sin theta
2 x^2 - x - 1 = 0
Complete the Square after dividing by 2
x^2 - 1/2 x + 1/16 - 1/16 - 1/2 = 0
( x - 1/4 )^2 - 9/16 = 0
( x - 1/4 )^2 = 9/16
( x - 1/4 ) = +- 3/4
x = 1 , -1/2
Substituting back
sin theta = 1 , -1/2
Taking the inverse sin of both sides
theta = pi/2 , 7pi/6 , 11pi/6