Answer
Undefined.
Work Step by Step
As $\frac{3\pi}{2}$ is along the $-y$ axis, $tan(\frac{3\pi}{2})$ is undefined.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.