Angles and their sums
Classify angles by size, read an angle from a protractor, work out a missing angle in a triangle or quadrilateral, and identify vertical and supplementary angles.
Available exercises
Classify an angle by its measure
Given the measure of an angle, name it: acute, right, obtuse or straight.
Measure an angle with a protractor
Read the measure of the angle shown on the protractor. Values are in steps of 10° (from 20° to 160°).
Angle sum in a quadrilateral
You know three angles of a quadrilateral. Work out the fourth — the sum is always 360°.
Angle sum in a triangle
You know two angles of a triangle. Work out the third — the sum is always 180°.