Question

sinx+ sin2x+sin3x  ; если x= пи/6

 

Answer 1

2sin2xcosx+sin2x=0

sin2x(2cosx+1)=0

1)sin 2x=П+Пn

sin x=П/2+Пn/2

2)cosx=-1/2

x=+-П/3+2Пn