sin^2х+sin^2 2х+sin^2 3х+sin^4х=2

(1-cos2x)/2+(1-cos4x)/2+(1-cos6x)/2+(1-cos8x)/2=21-cos2x+1-cos4x+1-cos6x+1-cos8x=4cos2x+cos4x+cos6x+cos8x=02cos5xcos3x+2cos5xcosx=02cos5x(cos3x+cosx)=02cos5x*2cos2xcosx=0cos5x=0⇒5x=π/2+πn⇒x=π/10+πn/5cos2x=0⇒2x=π/2+πn⇒x=π/4+πn/2cosx=0⇒x=π/2+πn