Question

1-2cos²ß:
cosß +sinß

Answer 1

$frac{1-2cos^2 beta }{cos beta +sin beta }=frac{sin^2 beta +cos^2 beta -2cos^2beta }{cos beta -sin beta }=frac{sin^2 beta -cos^2beta }{cos beta -sin beta } =\\= frac{(sin beta -cosbeta )(sin beta +cos beta )}{cos beta +sinbeta } = sin beta -cos beta$