Tangent - When an angle in a right angle is X, the tangent of x is the ratio of lengths of the side opposite x to the side adjacent to x.
Term - A part of an algebraic equation or a number in a sequence or a series or a product of real numbers and/or variables.
Tessellation - Congruent plane figures/shapes that cover a plane completely without overlapping.
Translation - A term used in geometry. Often called a slide. The figure or shape is moved from each point of the figure/shape in the same direction and distance.
Transversal - A line that crosses/intersects two or more lines.
Trapezoid - A quadrilateral with exactly two parallel sides.
Tree Diagram - Used in probability to show all of the possible outcomes or combinations of an event.
Triangle - Three sided polygon.
Trinomial - An algebraic equation with 3 terms - polynomial.