UPSC 2017 CDS I Math Paper

Let the length and breadth of the rectangle be x cm and y cm respectively.
Perimeter of the rectangle = 10 cm
∴2(x+y)=10⇒x+y=5
Area of the rectangle =4cm2
∴xy=4
⇒x(5−x)=4....(1)
From the given options, x = 4 satisfies equation (1).
Thus, the length of rectangleis 4 cm.