Question

Verify each of the following:

(ii)`cos 60^0 cos 30^0+ sin 60^0 sin30^0`

Answer 1

`cos 60^0 cos 30^0+ sin 60^0 sin30^0`

=`(1/2) xx(sqrt(3)/2) + (sqrt(3)/2) xx(1/2) = sqrt(3)/4 + sqrt(3)/4 =sqrt(3)/2` 

Also, cos `30^0 = sqrt(3)/2`

∴`cos 60^0  cos 30^0+ sin 60^0 sin30^0= cos 30^0`