Помогите пожалуйста(( 7√2Sin 15π/8*Соs15π/8

Question

Помогите пожалуйста((
7√2Sin 15π/8*Соs15π/8

Answer 1

7*√2*sin(15π/8)*cos(15π/8)=7*√2*√2*sin(15π/8)*cos(15π/8)/√2=
=7*2*sin(15π/8)*cos(15π/8)/√2=7*sin(15π/4)/√2

Comments

sin(15π/4)=sin ((16π/4)-(π/4))=sin ((4π)-(π/4))=-sin(π/4)=-√2/2