Question

What are the possible values of the angle θ if cos(θ)^2=1/2,and sin(θ)=−sqrt2/2? the values of θ are in radians and are between 0 and 2π?

Answer 1

5π/4, 7π/4

Explanation:

The sign of the sine tells you the angles of interest are in the 3rd and 4th quadrants. cos(θ) = ±√(1/2) tells you the reference angle is π/4 radians. The angles of interest are ...

π +π/4 = 5π/4

2π -π/4 = 7π/4