Geometry Vocabulary Flashcards
Acute angle
An angle that measures less than 90 degrees.
Obtuse angle
An angle that measures between 90 and 180 degrees.
Reflex angle
An angle that measures between 180 and 360 degrees.
Complementary angles
Two angles whose measures add up to 90°.
Right Angle
An angle of 90 degrees.
Supplementary angles
Two angles whose measures add up to 180°.
Straight-line angle
An angle of 180°.
Angles on a straight line
Angles that measure exactly 180 degrees.
Alternate angles
A pair of angles that form a shape of a z, or an n or an inverted z or n between a pair of parallel lines and a transversal. Alternate angles are equal in size.
Corresponding angles
A pair of angles that form a shape of an f, or an inverted f within a pair of parallel lines and a transversal. Corresponding angles are equal in size.
Interior angles
A pair of angles that form a shape of a u, within a pair of parallel lines and a transversal. Interior angles are supplementary.
Vertically opposite angles
When two intersecting lines meet at a single point, the opposite angles formed are equal and are called vertically opposite angles.
Exterior angle of a triangle
The exterior angle of a triangle is equal to the two opposite interior angles.
Angle sum of any quadrilateral
Interior angles of a quadrilateral always sum to 360°.
Exterior angles sum of a quadrilateral also is 360°.
Angle sum of a triangle
Interior angles of a triangle always sum to 180°.
Exterior angles sum of a triangle is 360°.
