Q11 of 186 Page 350

If A and B are acute angles such that sin A = cos B then (A + B) = ?

We are given that: sin A = cos B

∴We can rewrite it as: sin A = sin(90° – B)

On comparing both sides, we get,

90° – B = A

⇒ A + B = 90°

If sin 3A = cos (A – 10°) and ∠A is acute then ∠A = ?

If sec 4A = cosec (A – 10°) and 4A is acute then ∠A = ?

If cos (α + β) = 0 then sin (α – β) = ?

sin (45° + θ) – cos (45° – θ) = ?