cos^2 x + 2sin x cos x = 0
cos x (cos x + 2sin x) = 0
cos x =0
x = Pi/2 + Pi*k
cos x + 2sin x = 0 | : cos x
1 + 2 tg x = 0
tg x = -1/2
x = - arctg 1/2 + Pi*k
k = 0, x = Pi/2, x = -arctg 1/2
ответ: a) x = Pi/2 + Pi*k; x = -arctg 1/2 +Pi *k; b) Pi/2.
cos^2 x + 2sin x cos x = 0
cos x (cos x + 2sin x) = 0
cos x =0
x = Pi/2 + Pi*k
cos x + 2sin x = 0 | : cos x
1 + 2 tg x = 0
tg x = -1/2
x = - arctg 1/2 + Pi*k
k = 0, x = Pi/2, x = -arctg 1/2
ответ: a) x = Pi/2 + Pi*k; x = -arctg 1/2 +Pi *k; b) Pi/2.