Question

Тригонометрия

cos^2a-cos^4a/sin^2a-sin^4a

Answer 1

$\frac{ {cos}^{2}a - {cos}^{4}a }{ {sin}^{2} a - {sin}^{4}a } = \frac{ {cos}^{2}a }{ {sin}^{2}a } \times \frac{(1 - {cos}^{2} a)}{(1 - {sin}^{2}a)} =$

$= {ctg}^{2}a \times \frac{ {sin}^{2}a }{ {cos}^{2}a} = {ctg}^{2} a \times {tg}^{2} a = 1$