Two equal circles touch each other externally at a point $C$. If $AB$ is their common tangent then $\angle ACB$ $=$ $\left(45^{\circ}, 90^{\circ}, 40^{\circ}\right)$
$PQ$ is a tangent from an external point $Q$ to the circle with centre $O$. If $\triangle OPQ$ is an isosceles triangle then $\angle OQP =$ $\left(45^{\circ}, 90^{\circ}, 60^{\circ}\right)$