Вычислите: cos3π/8*sin19π/8 - sin3π/8*sin7π/8

Question

Вычислите: cos3π/8*sin19π/8 - sin3π/8*sin7π/8

Answer 1

=cos3n/8*sin(2n-3n/8)-sin3n/8*sin(n/2+3n/8)=cos3n/8*sin3n/8-sin3n/8*cos3n/8=0