A triangle ABC is inscribed in a circle so that AB is the diameter of the circle. Find the angles of a triangle if the arc AC is 70 degrees.

Since in the ABC triangle the side AB is the diameter of the circle, the inscribed angle ACB rests on the arc AB, the degree measure of which is 180, then the angle ACB = 180/2 = 90, and therefore the triangle ABC is rectangular.
The inscribed angle ABC rests on the arc AC, the degree measure of which, according to the condition, is 700, then the angle ABC = 70/2 = 45.
Then in a right-angled triangle ABC the angle BAC = (90 – 45) = 45.
Answer: The angles of triangle ABC are 90, 45, 45.