Question

Simplify the expression sin^2x-1/cos(-x)

Answer 1

Use the Pythagorean identity
`sin ^(2) x+cos ^(2) x=1`
to simplify the numerator.

`sin ^(2) x-1=-cos ^(2) x`
Now use that fact that

`cos(-x)=cos(x)` to set up the equivalent fraction:

`(sin ^(2)x-1 )/(cos(-x)) = (-cos ^(2)x )/(cos(x))`
Now reduce between the numerator and denominator to get -cos(x)