Question

Упростите     sin (Pi-α) sin(Pi/2 + α) / cos²α-1/2

Answer 1

=2sinacosa/(2cos²a-1)=sin2a/cos2a=tg2a

Answer 2

$frac{sin( pi - alpha )sin( frac{ pi }{2}- alpha ) }{cos ^{2} alpha - frac{1}{2} }= frac{2sin alpha cdot cos alpha }{2cos ^{2} alpha -1 }= frac{sin2 alpha }{cos2 alpha }=tg2 alpha$