Definitions and Symbols © 2008 Mr. Brewer

A flat surface that never ends

An exact location. A Read - point A Write - A

A straight figure with two endpoints. AB Write Read – line segment ab ab

A straight figure with no endpoints and goes on forever in both directions. GH Write - Read – line GH GH

A straight figure with one end point. It goes on forever in one direction BA BA WriteRead – ray BA

An angle is formed by two rays with the same endpoint Q R P Read – angle PQR or angle RQP or angle Q Write - PQR QRQP

A common endpoint of two rays or line segments. vertex

When the two sides of an angle form a square corner. The angle measures 90 0.

An angle that measures less than Angle measures less than 90 0

An angle that measures more than Angle measures more than 90 0

Lines that meet or cross at a common point AB and Write - CD intersect at point E A D C B E

Intersecting lines that form right angles. F I H G J Read – line FG is perpendicular to line HI HI Write - FG

Lines in the same plane that never cross Read – line KL is parallel to line MN M N KL KL Write - KL

A plane figure where all the points on the circle are the same distance from the center. A circle is named by its center point. A Circle A

A point in the center of a circle. Center

Any line segment with endpoints at the center of the circle and on the circle. Any line segment with endpoints at the center of the circle and on the circle. BC BC is a radius B of circle B C B

Any line segment that passes through the center of the circle and has both endpoints on the circle. Twice the length of the radius. Any line segment that passes through the center of the circle and has both endpoints on the circle. Twice the length of the radius. CD CD is a diameter B of circle B C D B

A path that begins and ends at the same point and does not cross itself

A closed figure formed from line segments that do not cross. Polygon means, “Many Angles.” Most polygons are named for the number of angles it has. Ex. Tri means 3… Triangle “Must have 3 or more sides.”

A four sided polygon

A quadrilateral with opposite sides that are parallel and the same length 14 in. 8 in.

A quadrilateral with opposite sides that are parallel, the same length, and have all right angles 10 in All Right Angles 4 in 10 in

A quadrilateral with opposite sides that are parallel, all the sides are the same length, and have all right angles All Right Angles 4 in

A parallelogram with all four sides equal 22 in

A quadrilateral with exactly one pair of parallel sides Parallel Sides

A polygon with three sides A polygon with three sides

A triangle with one right angle. A triangle with one right angle.

A triangle whose sides are all equal in length A triangle whose sides are all equal in length 8 mm

None of the sides are equal in length 12 in 40 in 34 in

Two sides are equal in length Two sides are equal in length 20 cm 15 cm

Figures with exactly the same shape. They may or may not be the same size

Figures with exactly the same size and shape.

Movement of a figure along a line.

A movement of a figure over a line so that the figure faces in the opposite direction. The lines may be imaginary.

The movement of a figure around a point. 90 degree turn 180 degree turn

The movement of a figure around a point. 270 degree turn 360 degree turn

A figure has a line of symmetry if it can be folded so that its two parts match. The fold is called the line of symmetry.

A pair of numbers used to locate a point on a grid. The first number tell you to move across the X – axis. The second number tells you to move up or down the Y – axis. 3, 2 Says move 3 right Move 2 up to your point X Y

The starting point or the ordered pair ( 0, 0 ) X Y origin

A figure that has one or more lines of symmetry.