Question

How do you simplify `\sin ^ { 2} ( \frac { \pi } { 4} ) - \cos ^ { 2} ( \frac { \pi } { 4} )`?

Answer 1

`- cos (pi/2)`

Explanation:

Apply the trig identity:
`cos^2 a - sin^2 a = cos 2a`
In this case:
`sin^2 (pi/4) - cos^2 (pi/4) = -cos (pi/2)`