Q2 of 90 Page 8

Prove that :

sin 38° + sin 22°= sin 82°

Take L.H.S:


sin 38° + sin 22°





= 2 sin 30° cos 8°



= cos 8°


= cos (90° - 82°)


{cos (90° - A) = sin A}


= sin 82°


= R.H.S


Hence Proved


More from this chapter

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8

1

Express each of the following as the product of sines and cosines:

i. sin 12x + sin 4x


ii. sin 5x – sin x


iii. cos 12x + cos 8x


iv. sin 2x + cos 4x

 2

Prove that :

cos 100° + cos 20° = cos 40°

 2

Prove that :

sin 50° + sin 10° = cos 20°