Choose the correct option and justify your choice: sin2A = 2sinA is true when A = 0, 30, 45, 60
30∘
0∘
45∘
60∘
Solution:
The correct option is A = 0
sin2A = 2sinA given 2sinAcosA = 2sinA (∵sin2A = 2sinAcosA) 2sinAcosA - 2sinA = 0 2sinA(cosA - 1) = 0 Either sinA = 0 or cosA - 1 = 0 A = 0 or cosA = 1 ⇒ A = 0 Hence, option A is correct.