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Lines and Angles
lines and angles
Question | Answer |
---|---|
Point | is an exact position on a plane surface |
Line | is a set of points in a straight path that extends in opposite directions without ending |
Line Segment | is a part of a line between 2 end points |
Ray | is a part of a line that has 1 end point and extends in one direction without ending |
Parallel lines | 2 lines are parallel if they never cross and remain distances apart no matter how far they are extended |
Perpendicular Lines | 2 lines are perpendicular if they are right angles (90*) to each other |
Angle | Whenever lines meet we say they intersect. The point where lines meet is called an intersection or vertex |
Acute angle | Less than 90* smaller than a right angle |
Right angle | exactly 90* |
Obtuse angle | greater than 90* but smaller than 180* bigger than a right angle |
Straight angle | exactly 180* |
Reflex angle | greater than 180* but less than 360* bigger than a right angle |
Revolution angle | full 360* |
Complementary angles | two angles are complementary when they add up to 90* a (right angle) they don't have to be next to each other, just as long as the total is 90* |
Supplementary angles | two angles are complementary when they add up to 180* they don't have to be together, just as long as they add up to 180* |
Vertically opposite angles | are the angles opposite of each other when 2 lines intersect "vertical" in this case means they share the same vertex, not the usual meaning of up-down vertically opposite angle are equal |
Angles at point | angles around a point will always add up to 360* |