Question

In the interval `90^@<=A<=360^@`, what's the smallest value of A for which `cotA` is undefined?

Answer 1

`180^o`

Explanation:

`cotA=cosA/sinA`

And so `cotA` will be undefined when `sinA=0`

We're asked for the smallest value of A within the interval:

`90^o<=A<=360^o`

The sine ratio is 0 at `0^o +- n180^o` where n is a natural number. And so the smallest value of A within our allowable range that will make `sinA=0` and therefore make `cotA` undefined is `180^o`