Question

For `f(x)=tanx*cotx` what is the equation of the tangent line at `x=(pi)/2`?

Answer 1

There is no tangent at `x=pi/2`

Explanation:

`pi/2` is not in the domain of the function `f(x)=tanx*cotx`, so there is no tangent line at `x=pi/2`.

This is a bit of a trick question.
For all `x` in the domain of `f`, we have `f(x)=1`,
so the equation of the tangent at any `x` in the domain is `y=1`.
But `pi/2` is not in the domain.