Free Maths Calculator

Angles Calculator

Four angle tools in one: interior and exterior angles of any polygon, the missing angle of a triangle, angles on a straight line and angles around a point. Each answer quotes the angle fact being used, because naming the rule is usually worth a mark by itself.

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    Worked Example

    Two angles of a triangle are 50° and 60°. Find the third angle.

    1. Angles in a triangle add up to 180°
    2. Add the known angles:50 + 60 = 110°
    3. Take that from 180:180 − 110 = 70°

    Answer: 70°

    Try These Yourself

    What is the interior angle sum of a pentagon?Show answerHide answer

    Answer: 540°

    (5 − 2) × 180 = 3 × 180.

    Angles of 140° and 90° sit around a point with one more angle. Find it.Show answerHide answer

    Answer: 130°

    360 − 140 − 90 = 130.

    Each exterior angle of a regular polygon is 45°. How many sides has it?Show answerHide answer

    Answer: 8

    360 ÷ 45 = 8.