Basic Definitions
A line that extends indefinitely in one direction
Ray
A triangle with three unequal sides
Scalene
Two angles that sum to 90 degrees
Complementary angles
An angle that measures 90 degrees
Right angle
If a triangle is isosceles...
then its base angles are congruent
A location with no size or shape
Point
The point of concurrency in a triangle where the angle bisectors meet
Incenter
Angles in the same position on different vertices
Corresponding Angles
An angle measuring less than 90 degrees
Acute angle
If two angles form a linear pair...
Flat surface made up of points and extends indefinitely in all directions
Plane
The point of concurrency in a triangle of the medians
Two angles that are between two lines but on opposite sides of the transversal
alternate interior angles
An angle measuring more than 90 degrees
Obtuse angle
A triangle is equilateral...
Made up of points with no thickness or width
Line
The line that connects a vertex of a triangle to the midpoint opposite
Median
Two angles directly across from each other on intersecting lines
Vertical angles
An angle measuring exactly 180 degrees
Straight angle
If two triangles are congruent...
then all corresponding parts angles and sides are congruent
Points that lie on the same line
Collinear
The line that connects the midpoints of two sides of a triangle
Midsegment
A line or ray that divides an angle into two equal parts
Angle bisector
Two angles with the same measure
Congruent angles
The sum of the lengths of any two sides of a triangle...