Q3 of 90 Page 9

Show that:

i.


ii.

i. We know, 2 sin A cos B = sin (A + B) + sin (A – B)






{sin (-x) = - sin x}



{sin (180° - x) = sin x}






Hence Proved


ii. We know, 2 sin A cos B = sin (A + B) + sin (A – B)



Take L.H.S




{sin (-x) = - sin x}




= R.H.S.


Hence Proved


More from this chapter

All 90 →
1

Express each of the following as the sum or difference of sines and cosines:

(i) 2 sin 3x cos x


(ii) 2 cos 3x sin 2x


(iii) 2 sin 4x sin 3x


(iv) 2 cos 7x cos 3x

 2

Prove that :

i.


ii.


iii.

4

Prove that:

 5

Prove that: