Question

Помогите решить . Тригонометрия 9 класс

Answer 1

$frac{Sin ^{2}2 alpha -4Cos ^{2} alpha }{Sin ^{2}2 alpha +4Cos ^{2} alpha -4 } = frac{4Sin ^{2} alpha Cos ^{2} alpha -4Cos ^{2} alpha }{4Sin ^{2} alpha Cos ^{2} alpha +4Cos ^{2} alpha -4 }= frac{4Cos ^{2} alpha (Sin ^{2} alpha -1) }{4Sin ^{2} alpha Cos ^{2} alpha +4(Cos ^{2} alpha -1) } =$$frac{-4Cos ^{3} alpha }{4Sin ^{2} alpha Cos ^{2} alpha -4Sin ^{2} alpha }= frac{-4Cos ^{3} alpha }{4Sin ^{2} alpha (Cos ^{2} alpha -1) } = frac{-4Cos ^{3} alpha }{-4Sin ^{3} alpha } = ctg ^{3} alpha$