In a triangle, ABC is inscribed in a circle centered at point O, the angle C of this triangle is 61 degrees.

In a triangle, ABC is inscribed in a circle centered at point O, the angle C of this triangle is 61 degrees. Find the degree measure of the angle OAB.

So, by the property of inscribed angles, the angle AOB = 122 degrees, since the radii of the circle are equal, the triangle AOC is isosceles.
Knowing that the sum of the angles of the triangle = 180, we find OAB. OAB = 180-122 / 2 = 29 degrees.
Answer: OAB = 29