A triangle $ABC$ is given $BC=8$ and $AE=4$ and $BK=6,4$ are heights. Find $AC$ and $AB$.

So we can find the area of $ABC$: $$S=\dfrac{BC\cdot AE}{2}=16.$$
So $AC=\dfrac{2S}{BK}=\dfrac{32}{6,4}=5.$
How can I find $AB$ from here?