Find the value of sin 75° sin 15° + cos 75° cos 15°1. \(\frac {\s

1.	Find the value of sin 75° sin 15° + cos 75° cos 15°1. \(\frac {\sqrt3 + 1}{2}\)2. \(\frac {1}{2}\)3. 14. 0
Answer» Correct Answer - Option 2 : \(\frac {1}{2}\) Concept: cos x cos y - sin x sin y = cos (x + y) cos x cos y + sin x sin y = cos (x - y) Calculation: Here, we have to find the value of sin 75° sin 15° + cos 75° cos 15° As we know that, cos x cos y + sin x sin y = cos (x - y) ∴ sin 75° sin 15° + cos 75° cos 15° = cos 75° cos 15° + sin 75° sin 15° = cos (75° - 15°) = cos 60° = \(\frac {1}{2}\)

Find the value of sin 75° sin 15° + cos 75° cos 15°1. \(\frac {\sqrt3 + 1}{2}\)2. \(\frac {1}{2}\)3. 14. 0

Answer» Correct Answer - Option 2 : \(\frac {1}{2}\)

Concept:

cos x cos y - sin x sin y = cos (x + y)

cos x cos y + sin x sin y = cos (x - y)

Calculation:

Here, we have to find the value of sin 75° sin 15° + cos 75° cos 15°

As we know that, cos x cos y + sin x sin y = cos (x - y)

∴ sin 75° sin 15° + cos 75° cos 15° = cos 75° cos 15° + sin 75° sin 15°

= cos (75° - 15°)

= cos 60°

= \(\frac {1}{2}\)