### The length and breadth of a rectangle is $8 \space cm$ and $15 \space cm$. Find the radius of the circumcircle of this rectangle.

$8.5 \space cm$

Step by Step Explanation:
1. The following figure shows the rectangle $ABCD$ with its circumcircle,

$AB$ and $BC$ are the length and the breadth of the rectangle $ABCD$ and $AC$ is the diameter of the circumcircle of the rectangle $ABCD$.
According to the question, $AB = 15 \space cm,$
$BC = 8 \space cm.$
2. \begin{align} \text { Now, in the right-angled triangle } ABC, AC^2 & = AB^2 + BC^2 \\ \implies AC & = \sqrt { AB^2 + BC^2 } \\ & = \sqrt { (15)^2 + (8)^2 } \\ & = 17 \space cm \end{align}
3. The diameter of the circumcircle of the rectangle $= 17 \space cm$.
The radius of the circumcircle of the rectangle $= \dfrac { 17 }{2} = 8.5 \space cm$.