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geometry definitons

Geometry definitons

acute triangle A triangle in which all three angles are acute
angle A figure formed by two rays that have a common endpoint
chord A line segment with its endpoints on a circle
circle A closed plane figure with all points on the figure the same distance from the center
circumference The distance around a circle
closed figure A figure that begins and ends at the same point
cone A solid figure that has a circular base and one vertex
congruent Having the same size and shape
congruent figures Figures that have the same size and shape
coordinate plane A plane formed by two intersecting and perpendicular number lines called axes
coordinates The numbers in an ordered pair
cube A solid figure with six congruent square faces
cylinder A solid figure that has two parallel bases that are congruent circles
degree (°) A unit for measuring angles and temperature
diameter A line segment that passes through the center of a circle and has its endpoints on the circle
dimension A measure in one direction; the length, width, or height of a figure
edge The line segment where two faces of a solid figure meet
equilateral triangle A triangle with three congruent sides
face A polygon that is a flat surface of a solid figure
figurate numbers Numbers that can be represented by geometric figures
hexagon A polygon with six sides and six angles
hypotenuse In a right triangle, the side opposite the right angle; the longest side in a right triangle
intersecting lines Lines that cross at exactly one point
isosceles triangle A triangle with two congruent sides
line A straight path in a plane that goes on forever in opposite directions
line segment A part of a line that includes two points, called endpoints, and all of the points between them
line symmetry A figure has line symmetry if a line can separate the figure into two congruent parts
obtuse angle An angle whose measure is greater than 90° and less than 180°
obtuse triangle A triangle that has one obtuse angle
octagon A polygon with eight sides
ordered pair A pair of numbers used to locate a point on a coordinate plane; the first number tells how far to move horizontally and the second number tells how far to move vertically
parallel lines Lines in a plane that never intersect
parallelogram A quadrilateral whose opposite sides are parallel and congruent
pentagon A polygon with five sides
perpendicular lines Two lines that intersect to form four right angles
pi The ratio of the circumference of a circle to its diameter
plane A flat surface that extends without end in all directions
plane figure A figure which lies in a plane
point An exact location in space, usually represented by a dot
point symmetry When a figure can be turned half way about a central point and still look the same
polygon A closed plane figure formed by three or more line segments
polyhedron A solid figure with flat faces that are polygons
prism A solid figure that has two congruent, polygon-shaped bases, and other faces that are all rectangles
protractor A tool used for measuring or drawing angles
pyramid A solid figure with a polygon base and all other faces triangles that meet at a common vertex
quadrilateral A polygon with four sides
radius A line segment with one endpoint at the center of a circle and the other endpoint on the circle
ray A part of a line, with one endpoint, that continues without end in one direction
rectangle A parallelogram with four right angles
rectangular prism A solid figure in which all six faces are rectangles
reflection (flip) A movement of a figure to a new position by flipping it over a line
regular polygon A polygon in which all sides are congruent and all angles are congruent
rhombus A parallelogram with four congruent sides
right angle An angle formed by perpendicular lines, line segments, or rays and with a measure of 90°
right triangle A triangle with one right angle
rotation (turn) A movement of a figure by turning it around a fixed point
rotational symmetry The property of a figure that can be rotated less than 360° around a central point and still be congruent to the original figure
scale drawing A drawing that shows a real object smaller than (a reduction) or larger than (an enlargement) the real object
scalene triangle A triangle with no congruent sides
similar figures Figures with the same shape but not necessarily the same size
solid figure A three-dimensional figure
sphere A solid figure that has the shape of a round ball; all points are the same distance from the center
square A rectangle with 4 equal sides
Created by: brandonnichols