What is the measure of z?

Step-by-step explanation:

Use altitude mean Theorem.

"If a triangle altitude splits it up into two right triangles and we are given the side left and right of the altitude then we can use the formula,

where a is the altitude, l is the left side of the altitude and r is the right side of the altitude.

We are trying to find the value of a, and we know the lr is

4*9=36

So we know the altitude is 6.

Know since the right triangle form a right triangle, apply Pythagoren Theorem