Answer :
4 cos2
θ − 4 cos θ + 1 = 04 cos2
θ − 4 cos θ + 1 = 04 cos2
θ − 4 cos θ + 1 = 04 cos2
θ − 4 cos θ + 1 = 04 cos2
θ − 4 cos θ + 1 = 04 cos2
θ − 4 cos θ + 1 = 0
4 cos2
θ − 4 cos θ + 1 = 04 cos2
θ − 4 cos θ + 1 = 04 cos2
θ − 4 cos θ + 1 = 04 cos2
θ − 4 cos θ + 1 = 04 cos2
θ − 4 cos θ + 1 = 04 cos2
θ − 4 cos θ + 1 = 0