JAMB 2011 · UTME · Q28

A circle of perimeter $28\text{ cm}$ is opened to form a square. What is the maximum possible area of the square?

Worked solution (try it first)

The length of wire does not change, so the square's perimeter is 28 cm.
Each side is $28 \div 4 = 7$ cm, so the area is $7^2 = 49\text{ cm}^2$ , option B.