Unit 1 - Foundations of Geometry Vocabulary

Congruent

• Having the same size and shape.

• Having different sizes but similar shapes.

• Having the same area but different shapes.

• Having no relation in size or shape.

Vertical Angles

• The angles adjacent to each other when two lines cross.

• The angles opposite each other when two lines cross. They are always equal.

• The angles formed by two parallel lines and a transversal.

• The angles that are supplementary to each other.

Complementary Angles

• Two angles whose measures add up to 90 degrees.

• Two angles that are equal in measure.

• Two angles that add up to 180 degrees.

• Two angles that are adjacent to each other.

Circle

• A round plane figure whose boundary consists of points equidistant from the center.

• A polygon with three sides.

• A shape with four equal sides and angles.

• An elongated shape with no corners.

Line

• A straight one-dimensional figure having no thickness and extending infinitely in both directions.

• A curved two-dimensional shape that encloses space.

• A solid three-dimensional object with length, width, and height.

• A point that has no dimensions and represents a location.

Angle Addition Postulate

• If a point lies in the interior of an angle, the sum of the two smaller angles is equal to the larger angle.

• The sum of the angles in a triangle is always 180 degrees.

• An exterior angle is equal to the sum of the two opposite interior angles.

• The angles opposite to equal sides of a triangle are equal.

Straight Angle

• An angle that is exactly 90 degrees.

• An angle that is exactly 180 degrees.

• An angle that is less than 90 degrees.

• An angle that is more than 180 degrees.

Right Angle

• An angle that is exactly 90 degrees.

• An angle that is less than 90 degrees.

• An angle that is more than 90 degrees but less than 180 degrees.

• An angle that is exactly 180 degrees.

Angle

• Formed by two rays with the same endpoint.

• A straight line that extends infinitely in both directions.

• A figure formed by three points that are not collinear.

• A measurement of the distance between two points.

Linear Pairs

• A pair of adjacent angles formed when two lines intersect.

• A pair of angles that are opposite each other when two lines intersect.

• A pair of angles that add up to 90 degrees.

• A pair of angles that are complementary but not adjacent.