2. Angles in opposite segments. When a quadrilateral is drawn inside a circle and their points touch the sides of the circle, the point at the top and the point at the bottom adds up to be 180°. This is called angles in opposite segments.













In this case, P and Q add up together to become 180°. In full: the sum of the angles in the opposite segments of a circle is 180°.Abbreviation: ∠s in oppo. segments Example:














∠ACB=90° (∠in a semicircle)∠y=180-90-60 =30° (∠s in oppo. segments)