# 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 truncatedcuboctahedron truncateddodecahedron truncatedicosahedron truncatedicosidodecahedron truncatedoctahedron truncatedtetrahedron

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 LineA tangent line is a line that intersects a circle or graph in just one local point.  Tangent lines are used a LOT in Calculus.  TetrahedronA 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 degreesFor 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. TrapezoidA 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.  TriangleA 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.  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 CubeThe 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 angleFor more info about Platonic solids, check out my Platonic solids gallery.  Truncated CuboctahedronThe 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 angleFor more info about Platonic solids, check out my Platonic solids gallery.  Truncated DodecahedronThe 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 angleFor more info about Platonic solids, check out my Platonic solids gallery.  Truncated IcosahedronThe 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 angleFor more info about Platonic solids, check out my Platonic solids gallery.  Truncated IcosidodecahedronThe 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 angleFor more info about Platonic solids, check out my Platonic solids gallery.  Truncated OctahedronThe 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 TetrahedronThe 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. A B C D E F G H I no J's K L M N O P Q R S T U V W no X's no Y's no Z's