Answer:
Step-by-step explanation:
Use identity:
- sin² α + cos² α = 1 ⇒ cos² α = 1 - sin² α = (1 + sin α)(1 - sin α)
Substitute this into given expression and simplify:
- cos² α / (sin α - 1) =
- (1 + sin α)(1 - sin α) / (sin α - 1) =
- - (1 + sin α) =
- - 1 - sin α
