We have to find the measure of angle AOB, being O the center of the circle.
The angles at the centre of a circle, like AOB, are twice the angle at the circumference of the circle of the same arc, like ACB.
Then, we can write:
[tex]m\angle AOB=2\cdot m\angle ACB=2\cdot25\degree=50\degree[/tex]
Answer: The measure of AOB is 50°.
