1)cos^2x-cos^2x+cos^2(3x)-cos^2(4x)=0 2)Sin^2(3x)+sin^2(4x)+sin^2(6x)+sin^2(7x)=2...

Question

1)cos^2x-cos^2x+cos^2(3x)-cos^2(4x)=0

2)Sin^2(3x)+sin^2(4x)+sin^2(6x)+sin^2(7x)=2 Помогите плиззз!!!

Answer 1

0+(1++cos6x)/2-(1+cos8x)/2=0
-(cos8x-cos6x)=0
2sin7xsinx=0
sin7x=0
7x=πk   sinx=0
x=πk/7  x=πkx
2)1-cos6x+1-cos8x+1-cos12x+1-cos14x=4
-(cos6x+cos14x)-(cos8x+cos12x)=0
2cos10xcos4x-2cos10xcos2x=0
cos10x(cos4x+cos2x)=0
x=π/20+πk/10
cos3xcosx=0
x=π/6+πk
x=π/2+πk