Question

In the given figure, $AOB$ is a diameter of the circle with center $O$ and $AC$ is a tangent to the circle at $A$. If $\angle BOC={130}^o$, then find $\angle ACO$.

Answer 1

$\angle OAC=90°(\because \text{Radius}\perp \text{Tangent})$

Therefore,

By exterior angle property,

$\angle BOC=\angle OAC+\angle ACO$

$\Rightarrow \angle ACO=130°-90°=40°$