Question

1-2cos^2b/cosb+sinb=? объясните плиз

Answer 1

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