88 terms

# Geometry Vocab

10/5/12
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Acute Angle
an angle less than 90 degrees but more than 0 degrees
Alternate Exterior Angles
Angles that lie outside a pair of lines and on opposite sides of a transversal.
Alternate Exterior Angles Converse
if two lines are cut by a transversal so that the alternate exterior angles are congruent, then the lines are parallel
Alternate Interior Angles Converse
if two lines are cut by a transversal so that alternate interior angles are congruent, then the lines are parallel
Alternate Interior Angles Theorem
if two parallel lines are cut by a transversal, then the pairs of alternate interior angles are congruent
Angle
A point and 2 line segments
Angle Addition Postulate
if point B lies in the interior of <AOC then m<AOB+m<BOC=m<AOC
Angle Bisection
Occurs when a ray bisects an angle
Angle of rotation
angle formed by rays drawn from the center of rotation to a point and its image
Area
the number of square units needed to cover a flat surface
Base Angles Theorem
if two sides of a triangle are congruent, then the angles opposite them are congruent
Between
The space between two points
Bisect
To cut into 2 equal pieces
Collinear (points)
points that lie on the same line
Compass
drafting instrument used for drawing circles
Complementary Angles
two angles whose sum is a right angle/90 degrees
Congruent
Having the same measure
Congruent Complements Theorem
if two angles are complementary to the same angle (or to congruent angles) then the two angles are congruent
Congruent Supplements Theorem
if two angles are supplementary to the same angle (or to congruent angles) then they are congruent
Conjecture
reasoning that involves the formation of conclusions from incomplete evidence
Construction
drawing a figure satisfying certain conditions as part of solving a problem or proving a theorem
Legs of a right triangle
the sides that make up the 90 degree angle of a right triangle
Consecutive Interior Angles
angles that are on the same side of the transversal and inside the two lines
Consecutive Interior Angles Converse
if two lines are cut by a transversal so that consecutive interior angles are supplementary, then the lines are parallel
Coordinate
a number that identifies a position relative to an axis
Coplanar
lying in the same plane
Counterexample
an example that shows a conjecture is false
Definition
clarity of outline
Direction of a vector
Determined by the angle that the vector makes with a horizontal line.
Distance
the property created by the space between two objects or points
Distance Formula
d = √[( x₂ - x₁) + (y₂ - y₁)]
Endpoints
points on the ends of line segments
Equiangular
all angles are congruent
Hypotenuse
the side of a right triangle opposite the right angle
Inductive Reasoning
reasoning from detailed facts to general principles
Image
a copy of a Preimage by a translation, rotation, ect...
Initial Point of a Ray
The endpoint on a ray
Integers
-3, -2, -1, 0, 1, 2, 3
Intersection
A point where two or more Lines, line segments, ect cross each other
Isosceles Triangle
A triangle with two congruent sides
Legs of an Angle
are the two congruent sides in a isosceles triangle
Legs of a Right Triangle
in a right triangle the sides that form the right angle are called legs of the right triangle. the side opposite the right angle is the hypotenuse of the triangle
Length
the linear extent in space from one end to the other
Linear Angle
Angle that is exactly 180 degrees
Linear Pair
Two adjacent angles that form a straight line
Linear Pair Postulate
If two angles form a linear pair, then they are supplementary
Line
A line with no endpoint
Line Segment
part of a line with two endpoints
Magnitude of a vector
AB is the distance from the initial point A to the terminal point B, and is written |AB|
Measure of an Angle
number of degrees in an angle
Midpoint
a point that divides a segment into two congruent segments
Midpoint Formula
(x₁+x₂)/2, (y₁+y₂)/2
Natural Numbers
each positive whole number
Ruler
measuring stick consisting of a strip of wood or metal or plastic with a straight edge that is used for drawing straight lines and measuring lengths
Opposite Rays
2 rays that have the same endpoint and go in opposite directions forming a line
Perpendicular Transversal
if a transversal is perpendicular to one of two parallel lines, then it is perpendicular to the other.
Plane
(mathematics) an unbounded two-dimensional shape
Point
Specific coordinate on a line, line segment, plane, ect...
Postulates
rules that are accepted without proof
Preimage
The original figure in a transformation.
Protractor
drafting instrument used to draw or measure angles
Ray
(mathematics) a straight line extending from a point
Rigid
fixed and unmoving
Segment Bisector
a segment, ray, line, or plane that intersects a segment at its midpoint
Sides of an Angle
the rays that form the angle
Straightedge
hand tool consisting of a flat rigid rectangular bar (metal or wood) that can be used to draw straight lines (or test their straightness)
Undefined Term
A basic figure that is not defined in terms of other figures. The undefined terms in Geometry are point, line, and plane.
Vertex
the point of intersection of lines or the point opposite the base of a figure
Right Angle
the 90 degree angle between two perpendicular lines
Obtuse Angle
an angle between 90 and 180 degrees
Perimeter
The distance around a figure
Straight Angle
An angle that is exactly 180 degrees
Real Numbers
Every number
Relection
The translation of a figure in which the object flips
Reflex Angle
an angle greater than 180 degrees (but less than 360)
Remote Interior Angles Theorem
the exterior angles of a triangle euquals the sum of the 2 remote interior angles.
Right Triangle
a triangle with one right angle
Right Angle Congruence Theorem
all right angles are congruent
Rotation
(mathematics) a transformation in which the coordinate axes are rotated by a fixed angle about the origin
Scalene Triangle
a triangle with no two sides of equal length
Sides of an Angle
the rays that form the angle
Supplementary Angles
Two angles whose sum is 180 degrees
Translation
(mathematics) a transformation in which the origin of the coordinate system is moved to another position but the direction of each axis remains the same
Triangle Sum Theorem
The sum of the measures of the angles of a triangle is 180.
vector
a straight line segment whose length is magnitude and whose orientation in space is direction
Verticle Angle
formed by 2 intersecting like and are opposites of each other which means angles are congruent
Verticle Angle Theorem
verticle angles are congruent
Whole Numbers
0 and the natural numbers