
an angle that measures less than 90 degrees 


2 angles that share a ray as a side 


2 rys that share an endpoint 


cuts an angle into 2 congruent parts. 


a triangle with 3 acute angles 


if 2 lines are cut by a transversal and the alternate interior angles are also congruent, then those 2 lines are parallel. 


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. 


the triangles are congruent if 2 angles and a side not part of the triangle are congruent to the corresponding part of another triangle. 


the triangles are congruent if one included side of the triangle are congruent to 2 angles and the included side of the other triangle. 


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. 


3 points on the same line, 2 points are always collinear 




4 more or more points on the same plane, 3 points are always coplanar 


2 angles that add up to 90 degrees (right angle) 


the “then” part of a conditional 


the “if” and “then” statement 




when the conclusion and hypothesis have changed in a conditional 


an example that tells its wrong 


when 2 lines are cut by a transversal for the corresponding angles to be congruent hen the lines are parallel. 


curved structure or line going inwards of a shape 


a surface that curves outwards of the shape 


2 angles in the same position along the transversal 


a statement that an be proved by using a theorem 


the lengh of a point to another 


trig to prove a statement by using postulates, theorems, and definitions 


distributing the number or variable to the numbers or variables that are inside of the parenthesis 




a line connecting 2 non adjacent vertices of a shape 


2 points the same distance from the 3rd point 


when 2 numbers have the same value 


a triangle with all congruent angles 


a triangle with all congruent sides 


an angle outside the parallel lines or figure 


information given when writting proofs 


the “if” part of a conditional 




the opposite side of the right angle in a right triangle 


lines that touch(at a point) planes that touch at a line) 


prediction or conclusion based on examples shown before 


angles between parallel lines cut by a transversal 


a triangle with 2 congruent sides 


an adjacent pair when their rays form a straight angle ( they always are supplementary 180) 


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 


the point that is equidistant from the points at the end of a line segment 


group of points that are not in the same line of a plane 


points not on the same plane 




an angle measuring more than 90 degrees 


a triangle with one obtuse angle 




a flat surface that extends in all directions 


represents a location/ vertex(smallest unit in geometry) 


a straight line that right angles to another line 


a rule that we think is true 


sequence of conclusions gotten out of an example trying to prove a statement 


when you tell apart a shape 


lines that never touch, going in the same direction 


planes that never touch going in the same direction 




a closed figure having 3 or more sides 


same as a proof except in a form of a paragraph 


a line that is perpendicular to the segment midpoint 




a series of points that extend in direction 


an angle measuring exactly 90 degrees 




a triangle with 1 right angle 


group of points that extend between 2 end points 


cuts a segment into 2 congruent parts 




an angle measuring exactly 180 degrees 


angles that sum up to 180 degrees 

same side interior angles 

two angles inside 2 lines on the same side of the transversal 


a triangle with no congruent sides 


the segments of a triangle 


lines in different planes that never touch and go in different directions 


when 3 sides of a triangle are congruent to the same sides of the other triangle 


if 2 sides of a triangle and the included angle are congruent to the same of the other triangle 


a rule that is proven to be true 


states any numbers that are equal 


proofs in the form of 2 columns (statements and reasons) 


a line that intersects coplanar lines in many different points 


a figure that has 3 sides and always measures 180 degrees 


the point where the sides of the angle meet 


pair of angles when they go across each other when 2 lines intersect 



vertex angle of an isosceles triangle 

the angle opposite of the base 


an angle measuring exactly 0 degrees 
