Cos5+cos85+sin75+sin15/4корень2*cos5*sin55

Question

Cos5+cos85+sin75+sin15/4корень2*cos5*sin55

Answer 1

Sin15/sin5 -sin75/cos5=sin15/sin5 -sin(90-15)/cos5=sin15/sin5 -cos15/cos5=
=(sin15*cos5-cos15*sin5)/sin5cos5=sin(15-5)/0,5sin10=sin10/0,5sin10=2