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Question
Find the perimeter of the rectangle whose length is 40 cm and a diagonal is 41 cm.
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Solution
Length of rectangle = 40 cm, Diagonal = 41 cm
Let the breadth of rectangle = x cm
From right angled triangle ΔABC,
AC2 = AB2 + BC2
(41)2 = (40)2 + BC2
BC2 = 1681 – 1600
BC2 = 81
BC = 9
Perimeter of rectangle = 2 (40 + 9)
= 2 × 49
= 98 cm
Hence, perimeter of rectangle = 98 cm
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