Question

If sin 2x = 4 cos x, then x is equal to

(a) \(\frac{nπ }{2}\) ± \(\frac{π }{4}\), n ∈ Z 

(b) No value 

(c)   \(nπ\) ± \((-1)^n\frac{π }{4}\), n ∈ Z 

(d)   \(2nπ\) ± \(\frac{π }{2}\), n ∈ Z 

Answer 1

Answer : (d)   2nπ ± \(\frac{π}{2}\), n ∈ Z 

sin 2x = 4 cos x

⇒ 2 sin x cos x = 4 cos x ⇒ 2 cos x (sin x – 2) = 0