Supplementary Angles Tool

Practice supplementary angles, angle equations, and angle relationships on a straight line with these related worksheets.

Watch these lessons to learn how to solve supplementary angle equations and find missing angle measures using angle relationships.

Drag the blue point to change one angle and watch how the adjacent angle changes.

Use the angle readouts to compare the two angle measures as the ray moves.

Use the equation display to connect the visual model to the fact that supplementary angles add to 180°.

The two angles form a straight angle, so their measures always add up to 180°.

When one angle gets larger, the other angle gets smaller by the same amount.

A visual angle relationship can be represented with an equation.

Angle: A figure formed by two rays that share the same endpoint.

Ray: A part of a line that has one endpoint and continues forever in one direction.

Line: A straight path that continues forever in both directions.

Vertex: The common endpoint where two rays meet to form an angle.

Degree: A unit used to measure the size of an angle.

Adjacent Angles: Angles that share a vertex and a side but do not overlap.

Straight Angle: An angle that measures exactly 180°.

Linear Pair: Two adjacent angles whose non-shared sides form a straight line.

Supplementary Angles: Two angles whose measures add up to 180°.

Complementary Angles: Two angles whose measures add up to 90°.

Angle Equation: An equation that uses angle relationships to find an unknown angle measure.

Supplementary angles have measures that add up to 180°.

\(m\angle A+m\angle B=180^\circ\)

A linear pair is made of adjacent angles that are supplementary.

\(\text{linear pair} \Rightarrow \text{supplementary angles}\)

Complementary angles have measures that add up to 90°.

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