acute angle
 an angle that measures less than 90 degrees
 2 angles that share a ray as a side
 angle
 2 rys that share an endpoint
 angle bisector
 cuts an angle into 2 congruent parts.
 acute triangle
 a triangle with 3 acute angles
 AIA converse
 if 2 lines are cut by a transversal and the alternate interior angles are also congruent, then those 2 lines are parallel.
 AIA theorem
 if a pair of parallel lines are cut by a transversal, then the alternate interior angles are congruent.
 alternate interior angles(AIA)
 2 non adjacent angles in between 2 lines on opposite sides of the transversal.
 AAS
 the triangles are congruent if 2 angles and a side not part of the triangle are congruent to the corresponding part of another triangle.
 ASA
 the triangles are congruent if one included side of the triangle are congruent to 2 angles and the included side of the other triangle.
 biconditional
 the “if and only if” statement used when the conditional and the converse are true.
 base of an isosceles triangle
 The thrid part, other than the legs is the base of a triangle(isosceles)
 Base angles of an isosceles triangle
 the angles of the base in the isosceles triangle.
 collinear
 3 points on the same line, 2 points are always collinear
 congruent
 equal in size and shape
 coplanar
 4 more or more points on the same plane, 3 points are always coplanar
 complementary angles
 2 angles that add up to 90 degrees (right angle)
 conclusion
 the “then” part of a conditional
 conditional
 the “if” and “then” statement
 congruent
 equal in size and shape
 converse
 when the conclusion and hypothesis have changed in a conditional
 counter example
 an example that tells its wrong
 CA converse
 when 2 lines are cut by a transversal for the corresponding angles to be congruent hen the lines are parallel.
 concave
 curved structure or line going inwards of a shape
 convex
 a surface that curves outwards of the shape
 correspomding angles
 2 angles in the same position along the transversal
 corollary
 a statement that an be proved by using a theorem
 distance
 the lengh of a point to another
 deductive reasoning
 trig to prove a statement by using postulates, theorems, and definitions
 distributive property
 distributing the number or variable to the numbers or variables that are inside of the parenthesis
 decagon
 a polygon with 10 sides
 diagonal
 a line connecting 2 non adjacent vertices of a shape
 equidistant
 2 points the same distance from the 3rd point
 equal
 when 2 numbers have the same value
 equilangular triangle
 a triangle with all congruent angles
 equilateral triangle
 a triangle with all congruent sides
 exterior angle
 an angle outside the parallel lines or figure
 given
 information given when writting proofs
 hypothesis
 the “if” part of a conditional
 hexagon
 a shape with six sides
 hypotenuse
 the opposite side of the right angle in a right triangle
 intersection
 lines that touch(at a point) planes that touch at a line)
 inductive reasoning
 prediction or conclusion based on examples shown before
 interior angle
 angles between parallel lines cut by a transversal
 isosceles triangle
 a triangle with 2 congruent sides
 linear pair
 an adjacent pair when their rays form a straight angle ( they always are supplementary 180)
 leg of a right triangle
 the other sides of the triangle other than the hypotenuse
 leg of an isosceles triangle
 the congruent sides of an isosceles triangle other than the base
 midpoint
 the point that is equidistant from the points at the end of a line segment
 noncollinear
 group of points that are not in the same line of a plane
 noncoplanar
 points not on the same plane
 nonogon
 a shape with 9 sides
 obtuse angle
 an angle measuring more than 90 degrees
 obtuse triangle
 a triangle with one obtuse angle
 octagon
 a shape with 8 sides
 plane
 a flat surface that extends in all directions
 point
 represents a location/ vertex(smallest unit in geometry)
 perpendicular
 a straight line that right angles to another line
 postulate
 a rule that we think is true
 proof
 sequence of conclusions gotten out of an example trying to prove a statement
 property
 when you tell apart a shape
 parallel lines
 lines that never touch, going in the same direction
 parallel planes
 planes that never touch going in the same direction
 pentagon
 a shape with 5 sides
 polygon
 a closed figure having 3 or more sides
 paragraph proof
 same as a proof except in a form of a paragraph
 perpendicular bisector
 a line that is perpendicular to the segment midpoint
 a shape having 4 sides
 ray
 a series of points that extend in direction
 right angle
 an angle measuring exactly 90 degrees
 reflexive property
 anything equal to itself
 right triangle
 a triangle with 1 right angle
 segment
 group of points that extend between 2 end points
 segment bisector
 cuts a segment into 2 congruent parts
 space
 a set of all points
 straight angle
 an angle measuring exactly 180 degrees
 supplementary angles
 angles that sum up to 180 degrees
 same side interior angles
 two angles inside 2 lines on the same side of the transversal
 scalene triangle
 a triangle with no congruent sides
 side of a triangle
 the segments of a triangle
 skew lines
 lines in different planes that never touch and go in different directions
 sas
 when 3 sides of a triangle are congruent to the same sides of the other triangle
 sss
 if 2 sides of a triangle and the included angle are congruent to the same of the other triangle
 theorem
 a rule that is proven to be true
 Transitive property
 states any numbers that are equal
 two column proof
 proofs in the form of 2 columns (statements and reasons)
 transversal
 a line that intersects coplanar lines in many different points
 triangle
 a figure that has 3 sides and always measures 180 degrees
 vertex
 the point where the sides of the angle meet
 vertical angles
 pair of angles when they go across each other when 2 lines intersect
 vertex of a triangle
 the points of a triangle
 vertex angle of an isosceles triangle
 the angle opposite of the base
 zero angle
 an angle measuring exactly 0 degrees