Question

МНОГО БАЛЛОВ !!!!
Упростите (1+tg(x))^2 + (1-tg(x))^2

Answer 1

$(1+tgx)^{2}+(1-tgx)^{2}=1+2tgx+tg^{2}+1-2tgx+tg^{2}x=2+2tg^{2}x=2(1+tg^{2}x)=\frac{2}{cos^{2} x}$