Prove that  =sin ² A cos ² A.

11
Prove:  = tan ² ϕ 12
Prove: (sec θ - tan θ) ²= . 14
If (a cos θ - b sin θ) = c, show that: (a sin θ + b cos θ) = . 15
Prove that 2(sin ⁶θ + cos ⁶θ ) - 3(sin ⁴θ +cos ⁴θ ) + 1 = 0.