Question

Evaluate the following:

2cos²60° + 3sin²45° – 3sin²30° + 2cos²90°

Answer 1

On substituting the values of various T-ratios, we get:

`2cos^2 60^circ + 3 sin^2 45^circ - 3 sin^2 30^circ + 2 cos^2 90^circ`

=`2xx(1/2)^2 + 3 xx(1/sqrt(2))^2 -3 xx (1/2)^2 + 2 xx (0)^2`

=`2xx1/4+3xx1/2-3xx1/4+0`

=`(1/2 +3/2-3/4)=((2+6-3)/4)=5/4`