Online Math Dictionary: T

Easy to understand math definitions for K-Algebra mathematics
Just scroll down or click on the word you want and I'll scroll down for you!

tangent	tangent line	tetrahedron
theorem	trapezoid	triangle
trigonometry	trinomial	truncate
truncated cube	truncated cuboctahedron	truncated dodecahedron
truncated icosahedron	truncated icosidodecahedron	truncated octahedron
truncated tetrahedron

Tangent
From trigonometry, the secant of an angle (in the picture below) is the ratio of the opposite side to the adjacent side:

For more trig info, check out my reference sections on The Trigonometry of Circles and The Trigonometry of Triangles.

Tangent Line
A tangent line is a line that intersects a circle or graph in just one local point. Tangent lines are used a LOT in Calculus.

tangent line on a circle

Tetrahedron A tetrahedron is a three dimensional geometric figure (a polyhedron) that is made up of 4 equilateral triangles. The tetrahedron is one of five very famous objects called The Platonic Solids.
Properties of the tetrahedron: 4 faces: equilateral triangles 4 vertices 6 edges Dihedral angle: about 70.53 degrees For more info about Platonic solids, check out my Platonic solids gallery.

Theorem
A theorem is a mathematical statement that has been proven to be true.

Trapezoid
A trapezoid is a quadrilateral that has a set of parallel sides. In the picture on the right, that's the top and bottom. These are called the bases of the trapezoid.
For more info on trapezoids, check out my Properties of Trapezoids page.

trapezoid

Triangle
A triangle is a three sided polygon. A triangle is officially defined by three points in space.

For more info on triangles, check out my Geometry and Trigonometry Reference Area.

triangle

Trigonometry
Trigonometry is the study of the geometry of triangles -- it's triangle geometry.

Trinomial
A trinomial is a polynomial with three terms.
Example:

Truncate
Truncate is just a fancy word for cutting something off.

Truncated Cube
The truncated cube is created by truncating (cutting off) the tips of the
cube one third of the way into each edge.
     Properties of the truncated cube
     14 faces: 8 equilateral triangles and 6 regular octagons
     24 vertices: 2 octagons and 1 triangle
     36 edges
     Dihedral angle: about 125.67 degrees for the oct-tri angle
                                  and 90 degrees for the oct-oct angle

For more info about Platonic solids, check out my Platonic solids gallery.

truncated cube

Truncated Cuboctahedron
The truncated cuboctahedron is created by truncating (cutting off) the cuboctahedronone third of the way into each side.
     Properties of the truncated cuboctahedron
     26 faces: 12 squares, 8 regular hexagons and 6 regular octagons
     48 vertices: 1 square, 1 hexagon and 1 octagon
     72 edges
     Dihedral angle: 135 degrees for the oct-sqr angle, about 125.27 degrees
                                    for the oct-hex angle and about 144.73 degrees for the
                                    hex-sqr angle

For more info about Platonic solids, check out my Platonic solids gallery.

truncated cuboctahedron

Truncated Dodecahedron
The truncated dodecahedron is created by truncating (cutting off) the tips of thedodecahedron one third of the way into each edge.
     Properties of the truncated dodecahedron
     32 faces: 20 equilateral triangles and 12 regular decagons
     60 vertices: 2 decagons and 1 triangle
     90 edges
     Dihedral angle: about 116.57 degrees for the dec-dec angle and
                                   about 142.62 degrees for the dec-tri angle

For more info about Platonic solids, check out my Platonic solids gallery.

truncated dodecahedron

Truncated Icosahedron
The truncated icosahedron is created by truncating (cutting off) the tips of theicosahedron one third of the way into each edge.
     Properties of the truncated icosahedron
     32 faces: 12 regular pentagons and 20 regular hexagons
     60 vertices: 2 hexagons and 1 pentagon
     90 edges
     Dihedral angle: about 138.183 degrees for the hex-hex angle and
                                   about 142.62 degrees for the hex-pent angle

For more info about Platonic solids, check out my Platonic solids gallery.

truncated icosahedron

Truncated Icosidodecahedron
The truncated icosidodecahedron is created by truncating (cutting off) theicosidodecahedron one third of the way into each side.
     Properties of the truncated icosidodecahedron
     62 faces: 30 squares, 20 regular hexagons and 12 regular decagons
     120 vertices: 1 square, 1 hexagon and 1 decagon
     180 edges
     Dihedral angle: about 148.283 degrees for the dec-sqr angle,
                                   about 142.62 degrees for the dec-hex angle and
                                   159.1 degrees for the hex-sqr angle

For more info about Platonic solids, check out my Platonic solids gallery.

truncated icosidodecahedron

Truncated Octahedron
The truncated octahedron is created by truncating (cutting off) the tips of the octahedronone third of the way into each edge.
     Properties of the truncated octahedron
     14 faces: 6 squares and 8 regular hexagons
     24 vertices: 2 hexagons and 1 square
     36 edges
     Dihedral angle: about 125.27 degrees for the sqr-hex angle,
                                   about 109.46 degrees for the hex-hex angle

For more info about Platonic solids, check out my Platonic solids gallery.

truncated octahedron

Truncated Tetrahedron
The truncated tetrahedron is created by truncating (cutting off) the tips of the tetrahedronone third of the way into each edge.
     Properties of the truncated tetrahedron
     8 faces: 4 equilateral triangles and 4 regular hexagons
     12 vertices: 2 hexagons and 1 triangle
     18 edges
     Dihedral angle: about 70.53 degrees for the hex-hex angle,
                                   about 109.47 degrees for the hex-tri angle

For more info about Platonic solids, check out my Platonic solids gallery.

truncated tetrahedron

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