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Geometry
| Term | Definition |
|---|---|
| Point | an exact location on a line, in a plane or in space |
| Line | A straight path of points that goes on forever in opposite directions |
| line segment | part of a line with two end points and all the points between them |
| ray | a part of a line that begins at one end point and goes on forever in one direction |
| plane | a flat surface of points that continues without end in all directions named by at least three points |
| intersecting lines | lines that cross each other at one point |
| parallel lines | lines in the same plane that never intersect and are always the same distance apart |
| perpendicular lines | lines that intersect to form four right angles (90 degrees) |
| angle | two rays with the same end point |
| vertex | end point at which two rays meet in an angle |
| protractor | tool used to measure the degree of an angle |
| right angle | an angle that measures exactly 90 degrees and forms a square corner |
| acute angle | angle that measures greater than 0 degrees and less than 90 degrees |
| obtuse angle | angle that measures greater than 90 degrees and less than 10 degrees |
| straight angle | angle that measures exactly 180 degrees and forms a line. |
| equilateral triangle | a triangle with 3 equal sides |
| isosceles triangle | a triangle with 2 equal sides |
| scalene triangle | a triangle with no equal sides |
| right triangle | a triangle that has a right angle (measures 90 degrees) |
| acute triangle | a triangle that has three acute angles that measure less than 90 degrees |
| obtuse triangle | a triangle that has one obtuse angle that measures more than 90 degrees |
| parallelogram | a quadrilateral with all sides parallel and opposite sides equal |
| rhombus | a parallelogram with four equal sides |
| trapezoid | a quadrilateral with only one pair of parallel sides |
| square | a plane figure with four equal sides and four right angles |
| rectangle | a plane figure with two pairs of equal sides and four right angles |
| polygon | a closed plane figure with sides formed by 3 or more line segments |
| triangle | a polygon with 3 sides and 3 angles |
| quadrilateral | a polygon with 4 sides and 4 angles |
| pentagon | a polygon with 5 sides and 5 angles |
| hexagon | a polygon with 6 sides and 6 angles |
| octagon | a polygon with 8 sides and 8 angles |
| regular polygon | a polygon in which all sides have equal length and all angles have equal measure |
| irregular polygon | a polygon in which all the sides are not equal length and the angles do not have equal measure |
| circle | a closed plane figure made up of many points that are the same distance from the center |
| center | the point from which every point in a circle is exactly the same distance |
| chord | a line segment that has its endpoints on the circle |
| diameter | a chord that passes through the center of a circle |
| radius | a line segment with one end point at the center of a circle and the other end point on the circle |
| compas | a tool used to construct circles |