Question

in circle b with the measure of arc $overset{\frown}{ac}=90^circ$, find $mangle abc$.

Explanation:

Step1: Recall central arc angle rule

The measure of a central angle is equal to the measure of its intercepted arc.

Step2: Match angle to its arc

$\angle ABC$ is the central angle intercepting arc $\overset{\frown}{AC}$.

Answer:

$90^\circ$