Question

упростите: (1+tg^2альфа)*(1-cos^2альфа)

Answer 1

$(1+tg^{2} \alpha )*(1-cos^2\alpha )=\frac{1}{cos^{2}\alpha} *(1-cos^2\alpha )=\frac{1}{cos^{2}\alpha}-1=tg^{2}\alpha$

Answer 2

$(1+tg^{2} \alpha )*(1-Cos^{2}\alpha )=\frac{1}{Cos^{2}\alpha}*Sin^{2} \alpha=\frac{Sin^{2}\alpha}{Cos^{2}\alpha}=tg^{2}\alpha$