| Shape | Term | Definition |
 | perpendicular line segments |
Two line segments which cross to form 90 degree angles. |
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right angle
| A 90 degree angle. |
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equilateral triangle
| A triangle with all sides equal and all angles equal. |
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scalene triangle
| A triangle having three unequal sides and angles. |
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vertex
| The intersection point of two sides of a plane figure. |
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right triangle
| A triangle with one internal angle equal to 90 degrees. |
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pentagon
| A polygon with 5 sides and 5 angles. |
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square
| A rectangle having all four sides of equal length. |
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intersecting line segments
| Line segments that cross each other. |
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acute angle
| An angle less than 90 degrees but greater than 0 degrees. |
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chord
| The line segment between two points on a given curve. |
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radius
| A straight line extending from the center of a circle or sphere to the circumference or surface. |
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line segment
| One part of a line. |
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line
| A continuous extent of length. |
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point
| A position in space. |
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parallelogram
| A quadrilateral having both pairs of opposite sides parallel to
each other.(Note: squares and rectangles are also quadrilaterals.) |
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rectangle
| A parallelogram having four right angles.(Note: a square is also a
rectangle.) |
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rhombus
| An equilateral parallelogram having oblique angles. |
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parallel line segments
| Line segments that do not intersect. |
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quadrilateral
| A polygon with four sides.(Note: squares, rectangles and trapezoids
are also quadrilaterals.) |
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octagon
| A polygon having eight angles and eight sides. |
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circle
| A closed plane curve consisting of all points at a given distance from a point within it called the center. |
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trapezoid
| A quadrilateral plane figure having two parallel and two nonparallel sides. |
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ray
| The part of a straight line considered as originating at a point on the line and as extending in one direction from that point. |
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closed curve
| A curve that is continuous and has endpoints that meet at the same
point. |
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isosceles triangle
| A triangle which has two sides equal. |
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hexagon
| A polygon having six sides and six angles. |
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diameter
| A straight line passing through the center of a circle or sphere and meeting the circumference or surface at each end. |
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obtuse angle
| An angle greater than 90 degrees but less than 180 degrees. |