8. Вычислите cos(5π/2) + sin(3π/2) − cos(7π/3) + sin(5π/2).

cos(5π/2) = 0, sin(3π/2) = −1, cos(7π/3) = 1, sin(5π/2) = 1.

0 − 1 − 1 + 1 = −1.

Ответ: −1.