Question

Решите уравнение:
-7sin2x-sinx=0

Answer 1

-7sin2x-sinx=0
-7*(2sinxcosx) - sinx = 0
sinx(14cosx - 1) = 0
1)  sinx = 0
x= πn, n∈Z
2)  14cosx - 1 = 0
14cosx - 1 = 0
cosx = 1/14
x = (+ -)*arccos(1/14) + 2πk, k∈Z