Решить а)5sin²x-14sinxcosx-3cos²x=2 б)3sin²3x+10sin3xcos3x+3cos²3x=0

1) 5sin²x-14sinxcosx-3cos²x - 2cos^2x - 2sin^2x = 0

3sin^2x - 5cos^2x-14sinx*cosx = 0  /  cos^2x не равн. 0

3tg^2x - 14tgx - 5 = 0

путь tgx = a , тогда

3a^2 -14a -5 = 0

Д = 196 + 60 = 256

х1 = (14+16) \ 6 = 5

х2= (14-16) \ 6 = -1\3

tgx = 5                tgx = -1/3

x=arctg5 + Пn       x= -arctg 1/3 +Пn