Вопрос в картинках...

Question

Решите задачу:

Answer 1

cos92=cos(90+2)=-sin2

cos182=cos(180+2)=-cos2

cos^2(2)+sin^2(2)=1

10/2=5

Answer 2

10/(cos^2 92 + 1 + cos^2 182) = 

10/(-sin^2 2 + 1  -  cos^2 2) = 10/(1-1)=10/0