Answer:
4 sqrt(7)
Explanation:
We can use the leg rule
hyp leg
------- = -------------------
leg part
9+7 z
------- = -------------------
z 7
Using cross products
(9+7) *7 = z^2
16*7 = z^2
112 = z^2
Taking the square root of each side
sqrt( 16*7) = sqrt(z^2)
4 sqrt(7) = z