a part of a line that starts at one endpoint and extends forever
Back
Vertical Angles
Front
A pair of opposite congruent angles formed by intersecting lines
Back
Obtuse triangle
Front
A triangle with one angle that is greater than 90 degrees.
Back
distance
Front
How far it is from one point to another
Back
Angle bisector
Front
a ray that divides an angle into two congruent angles
Back
Vertex angle
Front
The angle formed by the legs of an isosceles triangle.
Back
SSS postulate
Front
If three sides of one triangle are congruent to three sides of another triangle, then the triangles are congruent.
Back
Midpoint
Front
A point that divides a segment into two congruent segments
Back
triangle sum theorem
Front
The sum of the measures of the interior angles of a triangle is 180 degrees
Back
adjacent angles
Front
Two angles that share a common side and have the same vertex
Back
y-intercept
Front
The point where the graph crosses the y-axis
Back
complementary angles
Front
Two angles whose measures add to 90 degrees.
Back
Angle addition postulate
Front
If P is in the interior of <RST, then m<RSP + m<PST = m<RST
Back
Segment addition postulate
Front
If B is between A and C, then AB + BC = AC
Back
slope intercept form of a line
Front
Back
Congruent
Front
Having the same size and shape
Back
Isosceles triangle
Front
a triangle with at least two congruent sides
Back
transversal
Front
a line that intersects two or more coplanar lines at different points
Back
alternate interior angles
Front
angles between 2 lines and on opposite sides of a transversal
Back
perpendicular lines
Front
Lines that intersect to form right angles
Back
conclusion
Front
A summary based on evidence or facts
Back
Line
Front
1. A long thin mark on a surface. 2. A continuous extent of length, straight or curved, without breadth or thickness; the trace of a moving point. 3. Long, narrow mark or band.
Back
Scalene triangle
Front
a triangle with no congruent sides
Back
Supplementary angles
Front
Two angles whose sum is 180 degrees
Back
coplanar
Front
points that lie on the same plane
Back
AAS postulate
Front
If two angles and a non-included side of one triangle are congruent to two angles and a non-included side of another, then the two triangles are congruent.
Back
Linear Pair
Front
A pair of adjacent angles whose noncommon sides are opposite rays.
Back
Regular triangle
Front
All congruent sides and angles
Back
Acute triangle
Front
A triangle that contains only angles that are less than 90 degrees.
Back
Line segment
Front
A part of a line with two endpoints
Back
SAS postulate
Front
If two sides and the included angle of one triangle are congruent to two sides and the included angle of another triangle, then the triangles are congruent.
Back
corresponding angles
Front
Angles formed by a transversal cutting through 2 or more lines that are in the same relative position.
Back
parallel lines
Front
lines in the same plane that never intersect
Back
Right triangle
Front
a triangle with one right angle
Back
same side interior angles
Front
two interior angles on the same side of the transversal
Back
Segment bisector
Front
a segment, ray, line, or plane that intersects a segment at its midpoint
Back
HL Postulate
Front
If a hypotenuse and leg of one right triangle are congruent to the corresponding hypotenuse and leg of a second right triangle, then the triangles are congruent.
Back
Collinear
Front
Points that lie on the same line
Back
Equilateral triangle
Front
A triangle with three congruent sides
Back
conditional statements
Front
A statement that can be written in if-then form.
Back
hypothesis
Front
A testable prediction, often implied by a theory
An educated guess
Back
alternate exterior angles
Front
Angles that lie outside a pair of lines and on opposite sides of a transversal.