(Q22)Is it right to say that cos(60° + 30°) = cos 60° cos30° - sin 60° sin 30° .

L.H.S. = cos (60° + 30°)

cos ° =

R.H.S. = cos 60° . cos 30° - sin 60° . sin 30°.

=
1
.
√
2
 -
√
2
.
1
=
√
 -
√
 =

L.H.S. = R.H.S

Yes, it is right to say

cos (60° + 30°) = cos 60° . cos ° + sin 60° . sin °.

i.e., cos (A + B) = cos A . cos - sin A . sin