Question

If $\cos A=\frac{4}{5}$, find $\sin A$ and $\tan A$.

Answer 1

$\cos A=\frac{4}{5}=\frac{B}{H}$
$H^2=B^2+P^2$
$5^2=4^2+P^2$
$P^2=25-16=9$
$P=\sqrt{9}=3$
$\sin A=\frac{P}{H}=\frac{3}{5}$
$\tan A=\frac{P}{B}=\frac{3}{4}$