By Poonam

Verified by Ajay Kumar

If 2 × sin q × cos(90° − q) = 1/2, where 0° < q < 90°, then find the value of sin(2q) + cos(2q).

  1. (√2 − 1)/2

  2. (√3 − 1)/2

  3. (√3 + 1)/2

  4. (√2 + 1)/2

Answer: C

Solution

Since cos(90° − q) = sin q, 2 sin² q = 1/2, giving sin² q = 1/4. As q is acute, q = 30°. Therefore, sin 60° + cos 60° = √3/2 + 1/2 = (√3 + 1)/2.

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