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Tools of Geometry
Tools of Geometry Vocab Terms
Term | Definition |
---|---|
Line | Collection of points that extends to infinity in 2 directions / Name with 2 letters. |
Plane | Two dimensional surface that extends in all directions to infinity. Name with 3 letters. |
Space | The set of all points in three dimensions. |
Collinear | Points that lie on the same line. |
Coplanar | Points that lie on the same plane. |
Ray | A part of a line, with one endpoint, that continues without end in one direction. Half a line. |
Segment | A part of a line between two endpoints. |
Congruent | Having the same measure. |
Midpoint | A point that divides a segment into two congruent segments. |
Angle | A figure formed by two rays with a common endpoint. The endpoint is called the vertex. |
Vertex | The common endpoint of an angle |
Acute | Angle less than 90 degrees |
Obtuse | Angle greater than 90 degrees |
Right Angle | Angle that is 90 degrees |
Straight Angle | Angle that is 180 degrees |
Angle Bisector | A ray that cuts and angle in half |
Segment bisector | A point / line / plane that cuts a segment in half |
Opposite Rays | Two rays that have a common endpoint and form a line |
Vertical Angles | A pair of opposite congruent angles formed by intersecting lines |
Complimentary Angles | Two angles that add up to 90 degrees |
Supplementary Angles | Two angles whose sum is 180 degrees |
Adjacent Angles | Two angles that share a common side and have the same vertex. Angles next to each other. |
Linear Pair | Angles that share a common side and add up to 180 degrees. |
Skew | Lines that are in different planes and never intersect. |
Transversal Line | A line that intersects two or more lines |
Corresponding Angles | Lie on the same side of the transversal and in the same positions / congruent when the two lines are parallel |
Alternate Interior Angles | Interior angles of 2 lines and on opposite sides of a transversal / congruent when the two lines are parallel. |
Alternate Exterior Angles | Outside angles of a pair of lines and different sides of the transversal / congruent when the two lines are parallel |
Same Side Interior Angles | Interior angles that lie on the same side of the transversal, they are supplementary when the two lines are parallel. |
Same Side Exterior Angles | Two exterior angles on the same side of the transversal, they are supplementary when the two lines are parallel. |
Triangle Sum Theorem | All angle in a triangle add up to 180 degrees |
Exterior Angle Theorem | The measure of an exterior angle of a triangle is equal to the sum of the measures of the two remote interior angles. |
Isosceles Triangle Theorem | If 2 sides of a triangle are congruent, then the angles opposite those sides are congruent (base angles) |
Equiangular-Equilateral Triangle Theorem | All sides and angles in a triangle are congruent. Since the angles add up to 180 degrees, all angles are 60 degrees. |