Question

ABCD is a rectangle whose three vertices are B(4, 0), C(4, 3) and D(0, 3). Find the length of one of its diagonal.
[CBSE 2014]

Answer 1

The given vertices are B(4, 0), C(4, 3) and D(0, 3). Here, BD is one of the diagonals. So
$$\begin{gathered} BD=\sqrt{{\left(4-0\right)}^2+{\left(0-3\right)}^2} \\ =\sqrt{{\left(4\right)}^2+{\left(-3\right)}^2} \\ =\sqrt{16+9} \\ =\sqrt{25} \\ =5 \end{gathered}$$
Hence, the length of the diagonal is 5 units..