Recall:
The
tan of the measure of an angle is the ratio of the opposite side to the adjacent side to that angle, that is :

.
Since this ratio is 3/y, we denote the opposite side, and adjacent side respectively by 3 and y.
(Technically we should write 3t and yt, but we try our luck as we see y in the second ratio too!)
Similarly,

.
The adjacent side is already denoted by y, so we denote the length of the hypotenuse by z.
Now the sides of the right triangle are complete.

Answer: A