Question

докажите тождество (1+tg^2B)(1-cos^2B)=tg^2B

Answer 1

1) 1+tg² b = 1/Cos² b
2)  1 - Cos² b = Sin² b
3)  1/Сos² b ·Sin² b = Sin²b / Сos² b = tg ² b

Answer 2

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