Question

tg(a)×ctg(a) -1/sin²a​

Answer 1

Ответ:

$-ctg^{2}a$

Объяснение:

$tga \cdot ctga-\dfrac{1}{\sin^{2}a}=1-\dfrac{1}{\sin^{2}a}=\dfrac{\sin^{2}a-1}{\sin^{2}a}=-\dfrac{1-\sin^{2}a}{\sin^{2}a}=-\dfrac{\cos^{2}a}{\sin^{2}a}=-ctg^{2}a;$