- Acute angles of a right triangle: The acute angles of a right triangle that are complimentary
- Acute Triangles: All angles are less than 60 degrees
- Alternate exterior angles: Angles that lie on the opposite side of the transversal outside the parallel lines
- Alternate Extirior angles theorem: if two parallel lines are but by a transversal then the alternate interior lines angles are congruent.
- Alternate interior angles: Non-adjacent angles that lie on opposite sides of the transveral between the lines
- Auxiliary lines: a line that is added in aid of a proof
- Base: bottom of a triangle
- Conjecture: educated guess coming from inductive reasoning
- Coordinate Proof: A style of proof that uses geometry and algebra
- Corollary: The theorem that follows right after another theorem
- Corresponding angles: Angles that are congruent
- Corresponding Angles: Angles that lie on opposite sides of the transveral (aaah idk!)
- Corresponding angles Postulate: If two parallel lines are cut by a transversal then the pairs of corresponding angles are congruent.
- Corresponding sides: sides that are congruent
- Counter example: Disproving conjecture
- CPCTC: Corresponding parts of congruent triangles are congruent
- Deductive Reasoning: Using logic to draw conclusions from given facts
- Equiangular Triangle: All the angles are congruent
- Equilateral Triangle: When all the angle measures in an equalateral triangle are 60 degrees
- Exterior angle: An outside angle
- Exterior angles: the measure of an exterior angle of a triangle is equal to the sum of the measures of its remote intirior angles
- Included Angle: An angle created by two adjacent sides
- Included side: A common side of two executive angles
- Inductive reasoning: based on a pattern
- Interior: the set of all inside points
- Interior angle: An inside angle
- Isosceles Triangle: two sides and two angles of a triangle are congruent
- Legs of an isosceles: congruent sides in a isosceles triangle
- Obtuse triangle: One of the angles in a triangle is larger than 90 degrees
- Parallel lines: Coplanar lines that never intersect
- Parallel planes: planes that never interect
- Parallel sides Theorem: If 2 lines have the same slope than there parallel.
- Perpendicular bisector: a line perpendicular to a segment at the it's midpoint
- Perpendicular Lines Theorem: in a coordinate plane, two nonvertical lines are perpendicular if and only if the product of their slopes is -1. Verical and horisantal lines are perpendicular
- Point slope form: y-y=m(x-x)
- Remote intirior angle: An interior angle that is not adjacent to the extirior angle
- Right angle: An angle that is exactly 90 degrees
- Right Triangle: One of the angles on a triangle is equal to 90
- Rise: the difference in the y values on 2 points on the line
- Run: the difference in the x values on 2points on the line
- Same side intirior angles: if two parallel lines are but by a transversal then the same side interior angles are supplementary.
- Same-side interior angles: Angles that lie on the same side of the transversal between the parallel lines
- Scalene Triangle: All the measures of the sides are different
- Skew lines: lines that are not parallel but never intersect
- Slope: the ratio of rise to run (y-y) over (x-x) equation: y1 - y2 ove x1 - x2
- Slope intercept form: y=mx+b
- Theorem: Any statement you can prove
- Transversal: A line that intersects two parallel coplanar lines
- Triangle Rigidity: If the side lengths are given there is only one specific shape
- Triangle Sum theorem: The sum of all the angle measures of a triangle is 180 degrees
- two angles: If two angles of one triangle are congruent to two angles of another triangle then the 3rd angles is congruent
- Vertex: The angle formed by two legs