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3-D figure
45-45-90 triangle
Acute angle,
Acute triangle
Adjacent angles
Adjacent side
Algorithm
Alternate exterior angles
Alternate interior angles
Altitude
Altitude of a triangle
Ambiguous
Analytic geometry
Angle
Angle bisector
Angle measure between a line and a plane
Angle side
Angle-angle-angle (AAA) similarity
Antecedent
Arc
Arc length
Area
ASA
Automatic drawer
Axiom
Axis

Base
Base (base side) of a trapezoid
Base (base side) of a triangle
Biconditional
Bilateral symmetry
Box
Capacity
Cartesian plane
Center of a circle
Center of a rotation
Center of gravity
Central angle of a circle
Centroid
Chord of a circle
Circle
Circle circumscribed about a triangle
Circle inscribed in a triangle
Circularity
Circumcenter
Circumference
Clockwise
Coincidental lines
Collinear
Compass
Complementary angles
Composite transformation
Concave
Concave polygon
Concentric circles
Concentric circles
Concurrent lines
Conditional
Cone
Congruence transformation
Congruent
Congruent circles
Congruent figures
Congruent triangles
Conic section
Conic solid
Conjecture
Consecutive angles
Consecutive sides
Consecutive vertices
Consequent
Constant of an equation
Construction
Contraction
Contra positive
Converse
Converse theorem
Convex polygon
Convex quadrilateral
Convex set
Coordinate
Coordinate geometry
Coordinate plane
Coordinates
Coplanar
Corollary to a theorem
Corresponding angles
Cosine of an angle
Coterminal angles
Counterclockwise
Counterexample
Cross section
Cylinder
Cylindrical solid
Cylindrical surface
Decagon
Degree measure of an angle
Diagonal
Diameter
Dilation
Dimensions
Direction
Direction of a translation
Discrete Line
Distance
Distance between 2 parallel lines
Dodecagon
Dot
Drawing
Duodecagon
Edge
Empty set
Ends of a kite
Enneagon
Equal angles
Equal triangles
Equiangular
Equidistant
Equilateral
Equilateral triangle
Even node
Exclusive or
Existential statement
Expansion
Exterior angles
Exterior of an angle
Extremes
Face
Family tree
Frieze pattern
Fundamental region
Geometric mean
Given
Glide reflection
Goldback's Conjecture
Grade
Graph theory
Great circle

Grid
Half-plane
Harmonic mean
Hemisphere
Heptagon
Hexagon
Hidden lines
Hierarchy
Horizontal line
Hypotenuse
Icosahedron
Identity reflection
Identity transformation
If-Then statement
Image
Improper subset
Indenter
Infinite
Initial side
Inscribed angle
Instance of a sentence
Intercept
Interior angles
Interior of a circle
Interior of an angle
Intersecting planes
Intersection of two sets A and B
Inverse
Irrational number
Irregular polygon
Irregular region
Isometry
Isosceles trapezoid
Isosceles triangle
Kite
Lattice points
Leg of a right triangle
Limit
Line
Line number
Line of reflection
Line perpendicular to a plane
Line segment
Line symmetry or reflection symmetry
Linear equation
Linear pair
Linear term of an equation
Lines of sight
Location
Locus
Magnitude
Magnitude of a rotation
Magnitude of a translation
Major arc
Mapping
Matrix
Mean
Meaning
Means
Measure
Measure of an arc
Median
Median of a triangle
Midline
Midline theorem
Midpoint
Minor arc
Net
Network
N-gon
Node
Nonagon
Nonconsecutive angles
Nonconsecutive sides
Nonconsecutive vertices
Nonconvex set
Non-Euclidean geometry
Non-included side
Non-overlapping regions
Nonperspective drawing
Null set
Number line
Oblique line
Oblique prism or cylinder
Obtuse angle
Obtuse triangle
Octagon
Odd node
One-dimensional
One-sided interior angles
Opposite faces
Opposite rays
Opposite side
Ordered pair
Ordered triple
Orientation
Orthocenter
Overlapping triangles
Parallel lines
Parallel planes
Parallelepiped
Parallelogram
Pentadecagon
Pentagon
Perimeter of a polygon
Perimeter of a triangle
Perpendicular bisector
Perpendicular lines
Perpendicular planes
Perspective
Perspective drawing
Pi
Pixel
Plane
Plane figure
Plane geometry
Plane section
Platonic solid
Point
Point of concurrency
Point of intersection
Point of tangency
Polarity of a variable
Polygon
Polygonal region
Polyhedron
Postulate
Prism
Proof
Proof by contradiction
Proper subset

Proportion
Proportional
Protractor
Prove
Pyramid
Pythagorean theorem
Pythagorean triple
Q.E.D.
Q.E.F.
Quadrangle
Quadratic equation
Quadratic term of an equation
Quadrilateral
Radii
Radius
Radius of a circle
Rate
Ratio
Ratio of similitude
Ray
Rectangle
Rectangular solid
Reference angle
Refine
Reflecting line
Reflection
Reflection image
Reflection notation
Reflection symmetry
Reflex polygon
Region
Regular polygon
Regular pyramid
Resolution
Rhombus
Right angle
Right cone
Right cylinder
Right prism
Right triangle
Rotation
Rotation symmetry
SAS
Scale factor
Scalene triangle
Secant (line)
Secant to a circle
Sector
Segment
Semicircle
Set
Side of a polygon
Side-angle-side (SAS) congruence
Side-angle-side (SAS) similarity
Side-side-side (SSS) congruence
Side-side-side (SSS) similarity
Similar
Similar figures
Similar triangles
Similarity transformation
Sine of an angle
Size change
Size change factor
Size transformation
Skew lines
Slant height
Slide
Slope
Small circle
Solid
Solid geometry
Space
Sphere
Square

SSS
Straight angle
Subroutine
Subset
Sufficient condition
Supplementary angles
Surface
Surface area
Symmetry
Symmetry line
Tangent
Tangent (line)
Tangent of an angle
Tangram
Tessellate
Tessellation
Tetragon
Theorem
Three-dimensional
Tilt
Torus
Transformation
Transformation notation
Translation
Translation symmetry
Transversal
Trapezoid
Triangle
Triangle inequality
Triangulate
Tridecagon
Trigon
Two-dimensional
Undecagon
Union of two sets A and B
Universe
Van Hiele levels
Vanishing line
Vanishing point
Vector
Venn diagram
Vertex
Vertex angle
Vertex of a conic solid
Vertex of a polygon
Vertex of an angle
Vertical angles
Vertical line
View
Volume
Wedge
Zero angle
Zero-dimensional