A piece of wire when bent to from a circle will have a radius of 84 cm. If the wire is bent to form a square, the length of a side of the square is :

Answer: Option C

Given length of the piece of wire = 84 cm
Length of the piece of wire = Circumference of circle
$$\begin{array}{rl}& =2\pi r\\ & =2\times \frac{22}{7}\times 84\\ & =528cm\end{array}$$
Length of each side of square = a
∴ Perimeter of square = 4a = 528 cm
∴ Side of square = $$\frac{528}{4}$$ = 132 cm