Question

упростите, пожалуйста
ОЧЕНЬ СРОЧНО
АЛГЕБРА 10 КЛАСС

Answer 1

$frac{1-4Sin ^{2} alpha Cos ^{2} alpha }{2Cos ^{2} alpha -1}= frac{Sin ^{2} alpha +Cos ^{2} alpha -4Sin ^{2} alpha Cos ^{2} alpha }{Cos2 alpha }=$$frac{(Sin ^{2} alpha-2Sin ^{2} alpha Cos ^{2} alpha )+(Cos ^{2} alpha-2Sin ^{2} alpha Cos ^{2} alpha ) }{Cos2 alpha }=$$frac{Sin ^{2} alpha (1-2Cos ^{2} alpha )+Cos ^{2} alpha (1-2Sin ^{2} alpha ) }{Cos2 alpha } = frac{Sin ^{2} alpha *(-Cos2 alpha)+Cos ^{2} alpha *Cos2 alpha }{Cos2 alpha } =$$frac{Cos2 alpha(Cos ^{2} alpha -Sin ^{2} alpha ) }{Cos2 alpha } = Cos ^{2} alpha -Sin ^{2} alpha =Cos2 alpha$