Question

помогите с тождеством

Answer 1

$(1 + {tg}^{2} alpha ) {cos}^{4} alpha + {sin}^{2} alpha = 1 \ frac{1}{ {cos}^{2} alpha } times {cos}^{4} alpha + {sin}^{2} alpha = 1 \ {cos}^{2} alpha + {sin}^{2} alpha = 1 \ 1 = 1$