Câu `32` :

Ta có: `P = sin(a + π/4)sin(a - π/4) = (sin a cos π/4 + cos a sin π/4)(sin a cos π/4 - cos a sin π/4) = (sin a √2/2 + cos a √2/2)(sin a √2/2 - cos a √2/2) = 2/4(sin² a - cos² a) = 1/2(sin² a - cos² a) = -1/2 cos 2a`

Câu `33` :

Ta có: `P = (cos a + cos 5a + 2 cos 3a) / (sin a + sin 5a + 2 sin 3a) = (2 cos 3a cos 2a + 2 cos 3a) / (2 sin 3a cos 2a + 2 sin 3a) = 2 cos 3a (cos 2a + 1) / 2 sin 3a (cos 2a + 1) = cos 3a / sin 3a = cot 3a`

Câu `34` :

Ta có: `P = sin 30° cos 60° + sin 60° cos 30° = 1/2 * 1/2 + √3/2 * √3/2 = 1/4 + 3/4 = 4/4 = 1`

Đáp án :

Câu `32` : `D`

Câu `33` : `C`

Câu `34` : `A`