The perpendicular distance from a vertex in a polygon to its opposite side.

Two rays extending from a common end point called the vertex. Angles are measured in degrees

The line or plane of a geometric figure, from which an altitude can be constructed, upon which a figure is thought to rest.

The amount of space that can be filled in a container. Both capacity and volume are used to measure three-dimensional spaces; however, capacity usually refers to fluids, whereas volume usually refers to solids.

An angle that has its vertex at the center of a circle, with radii as its sides.

A data display that divides a circle into regions representing a portion of the total set of data. The circle represents the whole set of data.

A two-dimensional figure that divides the plane in which the figure lies into two parts—the part inside the figure and the part outside the figure (e.g., circles, squares, rectangles).

Two plane or solid figures are congruent if one can be obtained from the other by rigid motion (a sequence of rotations, reflections, and translations).

The units of measure developed and used in the United States.
Customary units for:

• length are inches, feet, yards, and miles.
• weight are ounces, pounds, and tons.
• volume are cubic inches, cubic feet, and cubic yards.
• capacity are fluid ounces, cups, pints, quarts, and gallons.

A three-dimensional figure with two parallel bases that are congruent circles.

A transformation that moves each point along the ray through the point emanating from a fixed center, and multiplies distances from the center by a common scale factor.

A line segment from any point on the circle passing through the center to another point on the circle.

Obtaining the measure of an object by using measuring devices, either standard devices of the customary or metric systems, or nonstandard devices such as a paper clip or pencil.

One of the plane surfaces bounding a three-dimensional figure; a side.

A line segment extending from the vertex or apex of a figure to its base and forming a right angle with the base or the plane that contains the base.

The longest side of a right triangle; the side opposite the right angle.

The measurement of an object through the known measure of another object.

A one-dimensional measure that is the measurable property of line segments.

A collection of an infinite number of points in a straight pathway with unlimited length and having no width

A portion of a line that consists of a defined beginning and endpoint and all the points in between.

The units of measure developed in Europe and used in most of the world. Like the decimal system, the metric system uses the base 10. Metric units for:
• length are millimeters, centimeters, meters, and kilometers.
• mass are milligrams, grams, and kilograms.
• volume are cubic millimeters, cubic centimeters, and cubic
meters.
• capacity are milliliters, centiliters, liters, and kiloliters.

Objects such as blocks, paper clips, crayons, or pencils that can be used to obtain a measure.

The point of intersection of the x- and y-axes in a rectangular coordinate system, where the x-coordinate and y-coordinate are both zero (0).

Two lines in the same plane that are a constant distance apart. Parallel lines never meet and have equal slopes.

Two lines, two line segments, or two planes that cross to form a right angle.

The symbol designating the ratio of the circumference of a circle to its diameter. It is an irrational number with common approximations of either 3.14 or 22/7.

An undefined, two-dimensional geometric surface that has no depth and no boundaries specified. A plane is determined by defining at least three distinct points or at least two distinct lines existing on the plane.

A specific location in space that has no discernible length or width.

A closed-plane figure, having at least three sides that are line segments and are connected at their end-points.

A three-dimensional figure whose base is a polygon and whose faces are triangles with a common vertex.

The square of the hypotenuse (c) of a right triangle is equal to the sum of the square of the legs (a and b), as shown in the equation c² = a² + b².

Any of the four regions formed by the axes in a rectangular coordinate system.

A line segment extending from the center of a circle or sphere to a point on the circle or sphere. Plural: radii.

A portion of a line that begins at an endpoint and goes on indefinitely in one direction.

A transformation that produces the mirror image of a geometric figure over a line of reflection.

A polygon that is both equilateral (all sides congruent) and equiangular (all angles congruent).

A cylinder in which the bases are parallel circles, perpendicular to the side of the cylinder

A three-dimensional figure (polyhedron) with congruent, polygonal bases and lateral faces that are all parallelograms.

A transformation of points in space consisting of a sequence of one or more translations, reflections, and/or rotations. Rigid motions here are assumed to preserve distances and angle measures.

A transformation of a figure by turning it counterclockwise about a center point or axis. The amount of rotation is usually expressed in the number of degrees (e.g., a 90º rotation).

The constant that is multiplied by the length of each side of a figure that produces an image that is the same shape as the original figure, but a different size.

A model or drawing based on a ratio of the dimensions for the model and the actual object it represents.

The numeric values, set at fixed intervals, assigned to the axes of a graph.

The edge of a polygon (e.g., a triangle has three sides) or one of the rays that make up an angle.

Figures that are the same shape, have corresponding, congruent
angles, and have corresponding sides that are proportional in length.

A term describing figures that are the same shape but are not
necessarily the same size or in the same position.

Three-dimensional figures that completely enclose a portion of space (e.g., a rectangular solid, cube, sphere, right circular cylinder, right circular cone, and square pyramid).

A three-dimensional figure in which all points on the figure are
equidistant from a center point.

Accepted measuring devices and units of the customary or metric system.

The sum of the areas of the faces and any curved surfaces of the figure that create the geometric solid.

A term describing the result of a line drawn through the center of a figure such that the two halves of the figure are reflections of each other across the line

An operation on a geometric figure by which another image is created. Common transformations include reflections (flips), translations (slides), rotations (turns) and dilations.

When the first element has a particular relationship to a second
element that in turn has the same relationship to a third element, the first has this same relationship to the third element (e.g., if a = b and b = c, then a = c).

If the length of object A is greater than the length of object B, and the length of object B is greater than the length of object C, then the length of object A is greater than the length of object C. This principle applies to measurement of other quantities as well.

A quantity with magnitude and direction in the plane or in space defined by an ordered pair or triple of real numbers.

The common endpoint from which two rays begin (i.e., the vertex of an angle) or the point where two lines intersect; the point on a triangle or pyramid opposite to and farthest from the base.

The opposite or non-adjacent angles formed when two lines intersect

The amount of space occupied in three dimensions and expressed in cubic units. Both capacity and volume are used to measure empty spaces; however, capacity usually refers to fluids, whereas volume usually refers to solids.

a part of a pattern or design that, when transformed using at least one type of symmetry transformation, will produce the entire design

a transformation that maps each point of a figure to its mirror image. where a line acts as athe mirror.

a figure or design that if rotated less than a full turn about a point to a position in which it looks the same as the original

a transformation that produces similar figures. the image of a figure under transformation has the same shape as the original figure but may be a different size