A right angle is exactly ¼ of a full 360 degree turn. When two straight lines intersect each other to form a right angle, the turn is measured as 90 degrees. Just think of it as slicing a pizza ...

Three sides of equal length andall the angles are 60 degrees. This is a scalene triangle ... you can find their value by halving 130°. Angles on a straight line also add up to 180°.