Unit 1 Vocabulary: Geometry

Line

• Consists of infinitely many points on a straight path that extends in two opposite directions with no end and no thickness.

• Is a geometric figure that has length but no width.

• Is a closed figure with three or more sides.

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

Segment Addition Postulate

• If B is between A and C, then AB + BC = AC.

• If A is between B and C, then AB + AC = BC.

• If C is between A and B, then AC + BC = AB.

• If A and C are endpoints, then AB + BC = AC.

Skew Lines

• Lines that intersect at a single point.

• Lines that do not intersect and are not coplanar.

• Lines that are parallel and in the same plane.

• Lines that intersect and are coplanar.

Angle Addition Postulate

• States that if two angles are complementary, their measures add up to 90 degrees.

• States that if you have two adjacent angles that share a common side, the measure of the larger angle is equal to the sum of the measures of the two smaller angles.

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

• States that vertical angles are always equal.

Angle

• A set of points consisting of two different rays that have the same endpoint.

• A figure formed by two lines that intersect at a point.

• A straight line that extends infinitely in both directions.

• A closed figure with three or more sides.

Acute Angle

• Measures greater than 0 degrees and less than 90 degrees.

• Measures exactly 90 degrees.

• Measures greater than 90 degrees and less than 180 degrees.

• Measures exactly 0 degrees.

Ray

• Defined as part of a line that has a fixed starting point (endpoint) and extends infinitely in one direction.

• A straight line that extends infinitely in both directions.

• A segment of a line with two endpoints.

• A point in space with no dimensions.

Point

• A location and has no size.

• A shape with length and width.

• A solid object with volume.

• A line that extends infinitely in both directions.

Parallel Lines

• Coplanar lines that do not intersect and have the same slope.

• Lines that intersect at a right angle.

• Lines that are always equidistant from each other but can intersect.

• Lines that are in different planes and do not intersect.

Collinear Points

• Points that lie on the same line.

• Points that are equidistant from each other.

• Points that form a triangle.

• Points that are located in different planes.