If cos 2 A = sin 75∘ , then the smallest positive value of A is:
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 7.5∘
According to the question,
Cos 2A = Sin 75°
⇒ Sin (90°- 2A) = Sin (75°)
Removing Sin From LHS and RHS
⇒ 90° - 2A = 75°
⇒ 2A = 90° - 75°
⇒ 2A = 15°
⇒ A = 15/2 = 7.5°