acute angle
an angle that measures less than 90 degrees
adjacent angles
2 angles that share a ray as a side
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.
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
equal in size and shape
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)
the “then” part of a conditional
the “if” and “then” statement
equal in size and shape
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.
curved structure or line going inwards of a shape
a surface that curves outwards of the shape
correspomding angles
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
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
a polygon with 10 sides
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
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
information given when writting proofs
the “if” part of a conditional
a shape with six sides
the opposite side of the right angle in a right triangle
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
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
 a shape with 9 sides
obtuse angle
an angle measuring more than 90 degrees
obtuse triangle
 a triangle with one obtuse angle
a shape with 8 sides
 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
parallel lines
lines that never touch, going in the same direction
parallel planes
planes that never touch going in the same direction
a shape with 5 sides
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
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
group of points that extend between 2 end points
segment bisector
cuts a segment into 2 congruent parts
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
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
Transitive property
states any numbers that are equal
two column proof
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
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