If sin 2A = 2 sin A, then A = ?

Question

Question

This question was previously asked in

NPCIL Assistant Grade-1 (HR/F&A/C&MM/Steno Grade-I) Official Paper-II (Held In: 2022)

Answer 1

Given:

sin 2A = 2 sin A

Formula used:

Using the double angle identity: sin 2A = 2 sin A cos A

Calculation:

sin 2A = 2 sin A

⇒ 2 sin A cos A = 2 sin A

⇒ 2 sin A cos A - 2 sin A = 0

⇒ 2 sin A (cos A - 1) = 0

Since sin A cannot be 0:

⇒ cos A - 1 = 0

⇒ cos A = 1

⇒ A = 0º

∴ The correct answer is option (1).

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