Question

а) sin^2+sin2x=1 б) cos^2x - sin 2x=1

Answer 1

sin^2x+2sinxcosx=cos^2x+sin^2x
sin^2x+2sinxcosx-cos^2x-sin^2x=0
2sinxcosx-cos^2x=0
2tgx-1=0
tgx=1/2
x=arctg1/2+pin n∈ Z