Answer
When x= 0 , $\tan\theta$ and $\sec\theta$ are undefined.
When y= 0 , $\cot\theta$ and $\csc\theta$ are undefined.
Work Step by Step
By Definition I-
$\tan\theta$ =$ \frac{y}{x}$
Hence it becomes undefined when x = 0, as division by 0 is not defined.
$\sec\theta$ =$ \frac{r}{x}$
Hence it becomes undefined when x = 0, as division by 0 is not defined.
$\cot\theta$ =$ \frac{x}{y}$
Hence it becomes undefined when y = 0, as division by 0 is not defined.
$\csc\theta$ =$ \frac{r}{y}$
Hence it becomes undefined when y = 0, as division by 0 is not defined.
