Index for Geometry Math terminology from plane and solid geometry. This includes basic triangle trigonometry as well as a few facts not traditionally taught in basic geometry.

AA Similarity

AAS Congruence

Abscissa

Accuracy

Acute Angle

Acute Triangle

Adjacent

Adjacent Angles

Alternate Angles

Alternate Exterior Angles

Alternate Interior Angles

Altitude

Altitude of a Cone

Altitude of a Cylinder

Altitude of a Parallelogram

Altitude of a Prism

Altitude of a Pyramid

Altitude of a Trapezoid

Altitude of a Triangle

Analytic Geometry

Angle

Angle Bisector

Angle of Depression

Angle of Elevation

Annulus

Antipodal Points

Apex

Apothem

Arc of a Circle

arccos

Arccos

arcsin

Arcsin

arctan

Arctan

Area of a Circle

Area of a Convex Polygon

Area of an Equilateral Triangle

Area of a Kite

Area of a Parallelogram

Area of a Rectangle

Area of a Regular Polygon

Area of a Rhombus

Area of a Sector of a Circle

Area of a Segment of a Circle

Area of a Trapezoid

Area of a Triangle

Arm of an Angle

Arm of a Right Triangle

ASA Congruence

Axes

Axis of a Cylinder

Axis of Reflection

Axis of Rotation

Axis of Symmetry

Base (Geometry)

Base of an Isosceles Triangle

Base of a Trapezoid

Base of a Triangle

Between

Bisect

Bisector

Box

Cartesian Coordinates

Cartesian Form

Cartesian Plane

Cavalieri’s Principle

Center of Rotation

Centers of a Triangle

Central Angle

Centroid

Centroid Formula

Ceva’s Theorem

Cevian

Chord

Circle

Circular Cone

Circular Cylinder

Circular Functions

Circumcenter

Circumcircle

Circumference

Circumscribable

Circumscribed

Circumscribed Circle

Coincident

Collinear

Complement of an Angle

Complementary Angles

Composite

Compression

Compression of a Geometric Figure

Compute

Concave

Concentric

Concurrent

Cone

Cone Angle

Congruence Tests for Triangles

Congruent

Consecutive Interior Angles

Contrapositive

Contraction

Convex

Coordinate Geometry

Coordinate Plane

Coordinates

Coplanar

Corresponding

cos

cos^{-1}

Cos^{-1}

cosine

CPCFC

CPCTC

Cube

Cube Root

Cuboid

Cylinder

Decagon

Degenerate

Degree (angle measure)

Diagonal of a Polygon

Diameter

Diametrically Opposed

Dihedral Angle

Dilation

Dilation of a Geometric Figure

Dimensions

Direct Proportion

Direct Variation

Directly Proportional

Disk

Distance Formula

Distinct

Dodecagon

Dodecahedron

Double Cone

Edge of a Polyhedron

Elliptic Geometry

Equation of a Line

Equiangular Triangle

Equidistant

Equilateral Triangle

Euclidean Geometry

Euler Line

Euler's Formula (Polyhedra)

Evaluate

Exact Values of Trig Functions

Exterior Angle of a Polygon

Face of a Polyhedron

Fibonacci Sequence

Fixed

Flip

Formula

Fractal

Frustum of a Cone or Pyramid

Geometric Figure

Geometric Mean

Geometric Solid

Geometry

Glide

Glide Reflection

Golden Mean

Golden Ratio

Golden Rectangle

Golden Spiral

Graph of an Equation or Inequality

Great Circle

Height

Height of a Cone

Height of a Cylinder

Height of a Parallelogram

Height of a Prism

Height of a Pyramid

Height of a Trapezoid

Height of a Triangle

Heptagon

Hero’s Formula

Heron’s Formula

Hexagon

Hexahedron

HL Congruence

HL Similarity

Horizontal

Hyperbolic Geometry

Hypotenuse

Icosahedron

Image of a Transformation

Incenter

Incircle

Inradius

Inscribed Angle in a Circle

Inscribed Circle

Interior

Interior Angle

Invariant

Inverse Cosine

Inverse Sine

Inverse Tangent

Isometry

Isosceles Trapezoid

Isosceles Triangle

Kite

Lateral Area

Lateral Surface Area

Lateral Surface/Face

Law of Cosines

Law of Sines

Leg of an Isosceles Triangle

Leg of a Right Triangle

Leg of a Trapezoid

Line

Line Segment

Linear

Linear Pair of Angles

Locus

Magnitude

Major Arc

Mean

Measure of an Angle

Measurement

Median of a Trapezoid

Median of a Triangle

Menelaus’s Theorem

Mensuration

Midpoint

Midpoint Formula

Minor Arc

Minute

Möbius Strip

Negative Reciprocal

n-gon

No Slope

Non-Adjacent

Nonagon

Noncollinear

Non-Convex

Non-Euclidean Geometry

Number Line

Oblique

Oblique Cone

Oblique Cylinder

Oblique Prism

Oblique Pyramid

Obtuse Angle

Obtuse Triangle

Octagon

Octahedron

Octants

One Dimension

Opposite Reciprocal

Ordered Pair

Ordered Triple

Ordinate

Origin

Orthocenter

Oval

Pappus’s Theorem

Parallel Lines

Parallel Planes

Parallel Postulate

Parallelepiped

Parallelogram

Pentagon

Perimeter

Perpendicular

Perpendicular Bisector

Phi (Φ φ)

Pi (Π π)

Plane

Plane Figure

Plane Geometry

Platonic Solids

Point

Point of Symmetry

Polygon

Polygon Interior

Polyhedron

Precision

Pre-Image of a Transformation

Prism

Proportional

Pyramid

Pythagorean Identities

Pythagorean Theorem

Pythagorean Triple

Quadrangle

Quadrants

Quadrilateral

Radian

Radical

Radicand

Radius of a Circle or Sphere

Ray

Rectangle

Rectangular Coordinates

Rectangular Parallelepiped

Reflection

Regular Dodecahedron

Regular Hexahedron

Regular Icosahedron

Regular Octahedron

Regular Polygon

Regular Polyhedra

Regular Prism

Regular Pyramid

Regular Right Prism

Regular Right Pyramid

Regular Tetrahedron

Rhombus

Riemannian Geometry

Right Angle

Right Circular Cone

Right Circular Cylinder

Right Cone

Right Cylinder

Right Prism

Right Pyramid

Right Regular Prism

Right Regular Pyramid

Right Square Prism

Right Triangle

Root of a Number

Rotation

SAA Congruence

SAS Congruence

SAS Similarity

Scale Factor

Scalene Triangle

Secant Line

Second

Sector of a Circle

Segment

Segment of a Circle

Self-Similarity

Semicircle

Semiperimeter

Shift

Side of an Angle

Side of a Polygon

Similar

Similarity Tests for Triangles

sin

sin^{-1}

Sin^{-1}

Sine

Skew Lines

Slant Height

Slope of a Line

SOHCAHTOA

Solid

Solid Geometry

Sphere

Square

Square Root

SSA

SSS Congruence

SSS Similarity

Standard Position

Stewart's Theorem

Straight Angle

Supplement

Supplementary Angles

Surd

Surface

Surface Area

Symmetric

Takeout Angle

tan

tan^{-1}

Tan^{-1}

Tangent (Trig Function)

Tangent Line

Tau (Τ τ)

Tessellate

Tetrahedron

Theorem of Menelaus

Theorem of Pappus

Theta (Θ θ)

Three Dimensional Coordinates

Three Dimensions

Torus

Transformations

Translation

Transversal

Trapezium

Trapezoid

Triangle

Triangle Congruence Tests

Triangle Inequality

Triangle Similarity Tests

Trig

Trig Functions

Trig Values of Special Angles

Trigonometry

Truncated Cone or Pyramid

Truncated Cylinder or Prism

Two Dimensions

Undecagon

Undefined Slope

Unit Circle

Varignon Parallelogram of a Quadrilateral

Vertex

Vertical

Vertical Angles

Volume

Washer

x-intercept

x-y Plane

x-z Plane

y-intercept

y-z Plane

z-intercept

Zero Dimensions

Zero Slope