Question

$ABC$ is a triangle right angled at $C$. If $AB=25cm$ and $AC=7cm$, find $BC$.

Answer 1

By applying Pythagoras theorem in $△ABC$,

$A{C}^2+B{C}^2=A{B}^2$
$\Rightarrow B{C}^2=A{B}^2-A{C}^2$
$\Rightarrow B{C}^2={25}^2-7^2$
$\Rightarrow B{C}^2=625-49$
$\Rightarrow B{C}^2=576$
$\Rightarrow \sqrt{BC}=\sqrt{576}$
$\Rightarrow BC=24cm$

Therefore, $BC=24cm$