Question

Solve the given equation and indicate the number of values of θ sach that 0≤θ<2π satisfy the iquation sin(2θ)+sin(θ)=0

Answer 1

sin(2θ)+sin(θ)=0

2sin(θ)cos(θ)+sin(θ)=0

sin(θ)[2cos(θ)+1)=0

so, sin(θ)=0 or 2cos(θ)+1=0 ===>>>> cos(θ)=(-1/2)

(θ) = 0 or (2pi/3)