Question

find the measure of the arc. macb = ?°

Explanation:

Step1: Recall arc - measure property

The measure of a major arc is 360° minus the measure of the corresponding minor arc. If the central angle of the minor arc is known, we can find the major - arc measure.

Step2: Assume central angle of minor arc

Let's assume the central angle of the minor arc $\overset{\frown}{AB}$ is $90^{\circ}$ (since the angle at the center is a right - angle as indicated in the circle).

Step3: Calculate measure of major arc $\overset{\frown}{ACB}$

The measure of the major arc $\overset{\frown}{ACB}=360^{\circ}-90^{\circ}$.
$m\overset{\frown}{ACB}=270^{\circ}$

Answer:

$270$