Mathematics for IGCSE & O level - Angles (Section 4 - No. 5)
In a quadrilateral, if three angles are 80°, 100°, and 60°, what is the measure of the fourth angle?
100°
110°
120°
130°
Paskaidrojums
Sum of angles in a quadrilateral is 360°. Therefore, the fourth angle is 360° - 80° - 100° - 60° = 120°.