Question

Cos(−θ)=√3/4 , sinθ<0 What is the value of sinθ ?

Answer 1

Since the length OQ = cos θ is the x-coordinate of P, and PQ = sin θ i

Answer 2

Hello : 
Cos(−θ)=√3/4

Cos(θ)=√(3)/2
sinθ = -1/2
θ = π + π/6 = 7π/6

θ = 2π - π/6 = 11π/6