ПОМОГИТЕ!!!!!!!!!!!!!!!!!

Question

ПОМОГИТЕ!!!!!!!!!!!!!!!!!

---

Answer 1

1. sin a = -3/5; a ∈ (3pi/2; 2pi). Значит, sin a < 0, cos a > 0.
cos a = √(1 - sin^2 a) = √(1 - 9/25) = √(16/25) = 4/5

2. sin(pi - a) = sin pi*cos a - cos pi*sin a = 0*cos a - (-1)*sin a = sin a