Q13 of 268 Page 4

Show by an example that
sin A + sin B ≠ sin (A + B)

Let A = 60^o and B = 30^o, then

L.H.S. = sin A + sin B = sin 60^o + sin 30^o

R. H. S. = sin (A + B) = sin (60^o + 30^o) = sin 90^o =1

∴ L.H.S. R.H.S

Show by an example that

cos A – cos B ≠ cos (A – B)

Show by an example that

cos C + cos D ≠ cos (C + D)

Show by an example that

sin A – sin B ≠ sin (A – B)

In a right hypotenuse AC = 10 cm and ∠A = 60°, then find the length of the remaining sides.

Show by an example thatsin A + sin B ≠ sin (A + B)