Question

Решите пожалуйста выражение!

Answer 1

cos2α=cos²α-sin²α
1)√2cos²(3π/8)-√2sin²(3π/8)=√2(cos²(3π/8)-sin²(3π/8))=
=√2cos(6π/8)=√2cos(3π/4)=√2(-√2/2)=-1
2)√3cos²(π/12)-√3sin²(π/12)=√3(cos²(π/12)-sin²(π/12))=
=√3cos(2π/12)=√3cos(π/6)=√3√3/2=3/2=1,5