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$