Question

Find the length of the diagonal of a rectangle whose sides are 4cm and 3cm

Answer 1

Use pythagorean theorem.
$\sqrt{3^2+4^2}=5$

The diagonal is 5cm

Answer 2

A rectangle contains 2 triangles which are divided by diagonals.
in this triangle length becomes the base .. breadth becomes height.
As this triangle is right angle triangle we can find the length by using pythogorean theorem.

Then , 2 sides were 4 cm and 3 cm respectively.

then using pythagorean theorem,
                $\sqrt{ 3^{2}+ 4^{2} }$  = $\sqrt{25}$
                                                             = 5
therefore the length of diagonal of a rectangle = 5 cm.

Hope this may helps u...........