1. main condition (contains the value which will become extreme):
2. additional conditions:
. Solve for h and plug this term into the equation of the main condition:
. You'll get the characteristic function of this problem:
Now calculate the derivative of V:
V has an extreme value (maximum or minimum) if V'(w) = 0. Calculate for w. (V'(w) = 0 if the numerator is zero and the denominator is not zero). You'll get two values for w. Only the positive value makes some sense.
My result for h = 4.68 m