Sin^2 x/6=1/2 2cos^2x+cos10x-1=0

Question

Sin^2 x/6=1/2
2cos^2x+cos10x-1=0

Answer 1

1)(1-cosx/3)/2=1/2
1-cosx/3=1
cosx/3=0
x/3=π/2+πn
x=3π/2+3πn
2)cos2x+cos10x=0
2cos6xcos4x=0
cos6x=0⇒6x=π/2+πn⇒x=π/12+πn/6
cos4x=0⇒4x=π/2+πn⇒x=π/8+πn/4