Помогите cos46°-cos74°

Question

Помогите cos46°-cos74°

Answer 1

cos46°-cos74° = 0.419

Answer 2

Используем формулу сosa-cosb=-2sin(a+b/2)sin)(a-b/2)
a=46   b=74    cos46°-cos74°=-2sin60sin14=-sin14/2