Problema Solution

A Rhombus has perimeter 180 cm and one of its diagonal is of length 72 cm. Find the length of the other diagonal.

Answer provided by our tutors

let


a = the wide of the rhombus, a>=0

d1 = 72 cm the diagonal of the rhombus, d1>=0

d2 = the other diagonal of the rhombus, d2>=0


the perimeter of a rhombus is 180 cm


4a = 180 => a = 180/4


a = 45 cm


the diagonals d1 and d2 of a rhombus bisect each other and are perpendicular.

using the Pythagorean Theorem we have


(d1/2)^2 + (d2/2)^2 = a^2


(72/2)^2 + (d2/2)^2 = 45^2


36^2 + (d2/2)^2 = 2025


by solving the equation we find and consider only the positive roots


d2 = 54 cm


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the length of the other diagonal is 54 cm.