Rectangles and axis of symmetry

Question

Lifeguards at a beach want to rope off a rectangular swimming section. They have 100 feet of rope with buoys. What is the maximum area that the swimming section can have?

Answer 1

s represents the length of the two equal sides

100 - 2s represents the length of the third side

A = s(100 - 2s)

A = 100s - 2s²

A = -2s² + 100s

Maximum occurs at -b/2a, or -100/-4, or 25

 

25 x 50 x 25