Question

From the given figure, find the value of $m$, if cos A $=\frac{3}{m}$,

Answer 1

Given: $\angle B={90}^{\circ }$, $AB=3$ and $BC=4$

In $△ABC$,

$A{B}^2+B{C}^2=A{C}^2$

$3^2+4^2=A{C}^2$

$A{C}^2=25$

$AC=5cm$
$\cos A=\frac{AB}{AC}=\frac{3}{5}$

$\text{but,}\cos A=\frac{3}{m}$

by comparing we get,

$m=5$