Answer:
h = 4∜17
Step-by-step explanation:
In a right triangle, if the legs are a and b, the hypotenuse is c, and the altitude to the hypotenuse is h, then using similar triangles,
a/h = h/H
h^2 = aH
so plug in your numbers. If the two you gave are the legs, then
h^2 = 4*4√17
h = 4∜17