If (2cosA + 1)(2cosA - 1) = 0, 0° < A ≤ 90°, then find the value of A.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 60°
Given:
(2cosA + 1)(2cosA - 1) = 0
Formula used:
a2 - b2 = (a + b)(a - b) ---- (1)
Calculations:
Using equation (1), we get
⇒ (2cosA + 1)(2cosA - 1) = 0
⇒ 4cos2A - 1 = 0
⇒ cos2A = 1/4
⇒ cos A = 1/2
⇒ A = 60°