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Discussion :: Area

1. The diagonal of a rectangle is 41 cm and its area is 20 sq. cm. The perimeter of the rectangle must be:

2.  A. 9 cm B. 18 cm C. 20 cm D. 41 cm

Explanation :

$$\sqrt{l^2+b^2}$$=$$\sqrt{41}$$

Also, lb = 20.

(l + b)2 = (l2 + b2) + 2lb = 41 + 40 = 81

(l + b) = 9.

Perimeter = 2(l + b) = 18 cm.

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