Question

show that sintita plus cos tita whole square plus sin tita -cos tita whole square is equals to 2​

Answer 1

(sin θ + cos θ)² + (sin θ - cos θ)² = 2

since it is in the form (a + b)² & (a-b)² we must use the identities...

on expanding,

sin² θ + 2 sin θ · cos θ + cos² θ + sin² θ - 2 sin θ · cos θ + cos² θ = 2

(sin² θ  + cos² θ) + (sin² θ  + cos² θ) = 2 [since (sin² θ  + cos² θ = 1)]

1 + 1 = 2

2 = 2

hence proved...