A Glossary of Mathematical Terms - T
Tally
A method of countign tghat is used to keep tarck of responses in
statistical surveys: 4 is talled as ////, or 
,
five is talled as 
or 
.
Tessellation
A covering or tiling of the plane with non overlapping shapes. Regular tessellations are made with regular polygons.
Tetragon
A four-sided polygon.
Tilt
The measure of an angle as compared to a horizontal line. (Also what happens when you kick the pinball machine too hard!).
Torus
A 3-D figure formed by rolling a rectangle into a cylinder and bending the cylinder until its bases meet.
Translation
See Slide.
Transversal
A line that intersects two other lines.
Trapezoid
A quadrilateral with two parallel sides.
Tree diagram
A diagram used in many circumstances; for example in statistics it represents a systematic way of determining all possible outcomes of an experiment.
Triangle
A three sided polygon.
Right triangle: when one angle is 90°.
Equilateral triangle: all angles are 60°, all sides have
equal length.
Isosceles triangle: a triangle with two sides of equal
length.
Scalene triangle: a triangle with three different sides and
angles.
Acute triangle: a traingle where all angles are less than
90°.
Obtuse triangle: a triangle with one angle that is more
than 90°.
Triangulate
To divide a polygon into triangles.
Tridecagon
A 13-sided polygon.
Trigon
The same as triangle.
Trigonometry
Basic elements: sine, cosine, tangent, cotangent, secant, cosecant.
Trinomial
A polynomial with three addends.