Science (English Medium) Class 11 - CBSE Question Bank Solutions

Express each of the following as the product of sines and cosines:
sin 2x + cos 4x

Prove that:
sin 38° + sin 22° = sin 82°

Prove that:
 cos 100° + cos 20° = cos 40°

Prove that:
sin 50° + sin 10° = cos 20°

Prove that:
 sin 23° + sin 37° = cos 7°

Prove that:
sin 105° + cos 105° = cos 45°

Prove that:
sin 40° + sin 20° = cos 10°

Prove that:
 cos 55° + cos 65° + cos 175° = 0

Prove that:
 sin 50° − sin 70° + sin 10° = 0

Prove that:
 cos 80° + cos 40° − cos 20° = 0

Prove that:
cos 20° + cos 100° + cos 140° = 0

Prove that:
\[\sin\frac{5\pi}{18} - \cos\frac{4\pi}{9} = \sqrt{3} \sin\frac{\pi}{9}\]

Prove that:

Prove that:

Prove that:

Prove that:

Prove that:

Prove that:

Prove that:
sin 47° + cos 77° = cos 17°

Prove that:
cos 3A + cos 5A + cos 7A + cos 15A = 4 cos 4A cos 5A cos 6A