Question

Упростить тригонометрическое выражение)

Answer 1

$frac{1}{Sin ^{2} alpha } -Ctg ^{2} alpha -Cos ^{2} alpha =1+Ctg ^{2} alpha -Ctg ^{2} alpha -Cos ^{2} alpha =1-Cos ^{2} alpha =$$=Sin ^{2} alpha \\ frac{1}{Cos ^{2} alpha } -tg ^{2} alpha -Sin ^{2} alpha =1+tg ^{2} alpha -tg ^{2} alpha -Sin ^{2} alpha =1-Sin ^{2} alpha =$$Cos ^{2} alpha$