Question

Cos3x/sin2x=1 при 170(градусов)<x<280(градусов)

Answer 1

Cos3x=sin2x
cos3x-cos(π/2-2x)=0
-2sin(x/2+π/4)sin(5x/2-π/4)=0
sin(x/2+π/4)=0
x/2+π/4=πk
x/2=-π/4+πk
x=-π/2+2πk,k∈z
sin(5x/2-π/4(=0
5x/2-π/4=πk
5x/2=π/4+πk
x=π/10+2πk/5,k∈z