My exam is tomorrow could you help me please

these are my problems

1\ f(x)=cos^2 (x) is it even or odd ?? show me the solution please

2\ verify the given identity :

cos 4x= 1- 8 cos^2 x + 8 cos^4 x

cos 3x - cos x = 4 cos^3 x - 4 cos x

sin 3x =3 sin x - 4 sin^3 x

3\find the exact value :

sin (2 sin^-1 4\5)

note sin^-1 = the inverse function of sin

please help me

regards ,

Nora