Verified answer

4sinx cosx + cos^2 x-sin^2 x = cos^2 x+sin^2 x

4 sinx cosx +cos^2 x-sin^2 x-cos^2 x-sin^2x = 0

4sinxcosx-2sin^2 x=0

2sinx(2cosx-sinx)=0

sinx =0     или  2cosx-sinx=0

x=пn                 2ctgx-1=0 (разделили всё на sinx)

                           ctgx=1/2

                            x=arcctg1/2 +пn

Ответ: пn; arcctg1/2+пn