If $A(5,1),B(1,4)\text{ and }C(8,5)$ are coordinates of the vertices of triangle$∆ABC$, then $∆ABC$ is 

In the given figure, $\mathrm{APB}$ is a tangent to a circle with centre $\mathrm{O}$ at point $\mathrm{P}$. If $\mathrm{\angle }\mathrm{Q}\mathrm{P}\mathrm{B}=50°,\mathrm{}$ then the measure of $\mathrm{\angle }\mathrm{P}\mathrm{O}\mathrm{Q}$ is