Thee size of angle ABC is 60 degrees. We write this as follows: To measure the size of angle PQR, place the protractor over the angle so that the centre of the protractor is directly over the angle's vertex, Q; and the base line of the protractor is along the arm, PQ, of the angle.

What is the sum of ANY triangle?

The sum of measures of these three angles of any triangle is invariably equal to the straight angle, also expressed as 180°, π radians, two right angles, or a half-turn.