Triangles/Angles Vocabulary

A closed shape with 3 sides and 3 angles. all interior angles add up to 180°.

• Square

• Triangle

• Rectangle

• Circle

The space between two intersecting lines.

Usually measured in degrees (°).

• Line

• Ray

• Angle

• Triangle

Angle less than 90°.

A triangle with all angles less than 90°.

• Acute

• Obtuse

• Straight

• Right

Angle greater than 90°.

A triangle with 1 angle greater than 90°.

• Acute

• Obtuse

• Straight

• Right

An angle that is exactly 90°.

A triangle with a 90° angle.

• Acute

• Obtuse

• Straight

• Right

A straight angle changes the direction to point the opposite way.

• Acute

• Obtuse

• Straight

• Right

Opposite angles made by two intersecting lines.

Angles are equal.

• Vertical

• Adjacent

• Supplementary

• Complementary

Two angles that have a common side and a common vertex (corner point) and don't overlap.

• Vertical

• Adjacent

• Supplementary

• Complementary

Two or more angles that add up to 90°

• Vertical

• Adjacent

• Supplementary

• Complementary

Two or more angles that add up to 180°

• Vertical

• Adjacent

• Supplementary

• Complementary