If $x-y=6$ and $xy=88$, then find the value of $x^3-y^3$.

In the given figure, if $\angle AOB=90°$ and $\angle ABC=30°$, then find the measure of $\angle CAO$.

$\text{If} 2^x=3^y=6^{-z}, \text{prove that} \frac{1}{x}+\frac{1}{y}+\frac{1}{z}=0.$

In the given figure, $PQRS$ is a square and $AB\Vert QS$. $M$ is the mid-point of $AB$. Prove that $PM$ bisects $\angle QPS$.