1.

The value of 2 sin 5π/12 cos π/12 will be:(A) 1(B) √3/2(C) √3/2 - 1(D) √3/2 + 1

Answer»

Answer is (D) √3/2 + 1

2 sin 5π/12  cos π/12

= 2 sin 75° cos 15°

= 2 sin (90° – 15°) cos 15°

= 2 cos 15° cos 15°

= 2 cos2 15°

= cos2 × 15° + 1

= cos 30° + 1

= √3/2 + 1 



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