Question

How to show? tan(90◦ − A) sec(180◦ + A) cos(90◦ + A) = 1

Answer 1

`LHS=tan(90^@− A) sec(180^@+ A) cos(90^@+ A)`

`=cotA(- secA)(- sin A)`

`=cosA/sinA*1/cosA*sin A`

`=1`