F(A)=3cosA+2sinA
Since cosA=-3/5 and sinA=4/5.
Substitution, F(A)=- 1/5
F(A)=√ 13sin(x+θ), where tanθ=3/2.
T=2π
x+θ=π/2+kπ
Axis of symmetry x=π/2-θ+kπ