Question

Find the perimeter of the rectangle whose length is \(40\) \(cm\) and a diagonal is \(41\) \(cm\).

Answer 1

In a rectangle, all interior angles are of \(90\degree\) measure. 
Therefore, Pythagoras theorem can be applied here.

\((41)^2= (40)^2 + x^2 \)

\(\Rightarrow\)\(1681\) = \(1600 + x\)

\(2 \times2= 1681 -1600\) = \(81\) 
\(x = 9 \) \(cm\)

\(Perimeter = 2(Length + Breadth)\)

= \(2(x + 40)\)

= \(2 (9 + 40)\)

= \(98\) \(cm\)