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21 Cards in this Set
- Front
- Back
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Ray |
A straight line that starts from a point, and continues forever. |
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Line |
A line passes between any two points, and keeps going in both directions. |
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Line segment |
The connection between two points on a line or ray. Because it is between two points, it has a starting and stopping point. |
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Intersection |
The point where a line, plane, ray, or line segment cross over or touch. A line intersects a line at a point, but when two planes cross over, they form a line. |
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Plane |
A 2 dimensional area. It has infinite length and width, but it has no depth. Any three points share a plane! |
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Collinear |
When points are on the same line. This is nothing special with two points, because you can draw a line connecting any two points. |
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Coplanar |
When points or lines share the same plane. This is nothing special with three points, because you can imagine a plane that any three points are on. |
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Parallel |
Coplanar lines that never touch. It has two l's in the middle, like parallel lines! Notice the arrow-marks in the middle of each line. Like the "same length" lines, these arrows get added to drawings to show when lines are parallel. |
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Bisector of a line segment |
A bisector is anything that intersects a line segment at its midpoint, or splits an angle into two equal halves. |
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Concurrent |
When lines/rays/segments run through a shared point. |
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Congruence |
The property of being alike in every way. Lines only need to have length in common, angles only need to have size in common, but figures need to have both angles and side length in common. If two shapes can lay exactly on top of each other (even if you need to flip or rotate one), they are congruent. |
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Two intersecting planes always form a... |
Line! In the image here, AB would be that line. |
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Opposite Angles |
When two (or more) straight lines intersect, the opposite pairs of angles are of equal size. |
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Complementary Angles |
Two angles that add to 90 degrees (C for complementary, C for corner!) |
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Supplementary Angles |
Two angles that add to 180 degrees (S for straight, S for supplementary!) |
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The sum of the angles in a triangle |
A triangle's interior angles add up to 180 degrees. |
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Acute angle |
An angle measuring less than 90 degrees |
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Obtuse angle |
An angle measuring greater than 90 degrees but less than 180 degrees |
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Right angle |
An angle measuring exactly 90 degrees |
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Reflex angle |
An angle greater than 180 degrees but less than 360 degrees |
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Staright angle |
An angle measuring exactly 180 degrees |
