Q9 of 53 Page 153

âPQRS is a rectangle. If PQ + QR = 7 and PR + QS = 10, then find the area of â PQRS.

PQ + QR = 7


PR + QS = 10


Since Diagonals of a rectangle are of equal length, so


PR = QS = 5


Let PQ be x, QR = 7 – x


Applying Pythagoras theorem :


x2 + (7 – x)2 = 52


2x2 – 14x + 24 = 0


x2 – 7x + 12 = 0


x2 – 4x – 3x + 12 = 0


x(x – 4) – 3(x – 4) = 0


(x – 3)(x – 4) = 0


x = 3, 4


The two sides are 3 and 4


Area of the Rectangle = (3 × 4) = 12 sq. units


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