Question

How do you find the limit of `phisecphi` as `phi->pi`?

Answer 1

`lim_(phi->pi) phi sec phi = -pi`

Explanation:

`phi sec phi = phi/cos phi`

The function is continuous in `phi = pi`, so that:

`lim_(phi->pi) phi sec phi = pi sec(pi) = pi/cos(pi) = -pi`