rectangle open on one side ??
Poor wording, I will assume that this is the "classic" problem where you have perimeter on only 3 sides, such as the rectangle is against a building.
b = 40 - 2h
A = bh
= h(40-2h)
= -2h^2 + 40h
dA/dh = -4h + 40
= 0 for a max of A
4h=40
h = 10
b = 40-20 = 20
The maximum area is 10(20) or 200 units^2
Given the area of a rectangle is A = bh, and assuming the rectangle is open on one side, perimeter b + 2h = 40, what formula will maximize the area of the rectangle
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