Question

Plz help me do 2 and 3​

Answer 1

Step-by-step explanation:

(2)

cos(2θ) tan θ + sin θ = 0

tan θ (cos(2θ) + cos θ) = 0

tan θ = 0

θ = kπ

cos(2θ) + cos θ = 0

cos(2θ) = -cos θ

cos(2θ) = cos(π − θ)

2θ = π − θ + 2kπ

3θ = (2k + 1) π

θ = (2k + 1) π / 3

Therefore, θ = kπ or (2k + 1) π / 3.

(3)

2 cos² θ − 2 cos²(2θ)

Power reduction formula:

1 + cos(2θ) − (1 + cos(4θ))

cos(2θ) − cos(4θ)