| A | B |
|---|
| point | indicates place or position; has no lenght, width or thickness |
| line | a set of points; can be straight, broken or curved |
| straight line | a line that extendes without end in both directions |
| plane | set of points suggested by a flat surface and extends endlessly in all directions |
| line segment | part of a line with two endpoints and all the points between |
| ray | part of a line that consists of one endpoint and all the points on one side of the endpoint |
| to name a ray | use 2 capital letters and an arrow going in the direction away from the endpoint; the first letter names the endpoint |
| opposite rays | two rays of the same line that have a common endpoint, but no other common points (thus forming a straight line) |
| angle | a set of points that is the union of two rays having the same endpoint |
| vertex | the common endpoint of two rays forming an angle |
| sides of the angle | are the two rays forming the angle |
| degrees | how angles are measured |
| right angle | measures 90 degrees |
| acute angle | measures less than 90 degrees, but more than 0 degrees |
| obtuse angle | measures more than 90 degrees, but less than 180 degrees |
| straight angle | measures 180 degrees, forming a straight angle and a straight line |
| perpendicular | two lines that intersect only at 90 degrees |
| adjacent angles | two angles on the same plane, having a common vertex and a common side |
| complementary angles | two angles whose sum of meaures is 90 degrees |
| supplementary angles | two angles whose sum of measures is 180 degrees |
| linear pair | two adjacent angles that are supplementary; the non-common sides form opposite rays (a straight line) |
| verticle angles | two nonadjacent angles formed by two intersecting lines; verticle angles are congruent |
| congruent | having equal measures |
| parallel lines | lines that lie in the same plane, but do not intersect |
| transversal | the line that cuts or intersects two other lines |
| alternate interior angles | pair of angles that are on OPPOSITE sides of the transversal and are IN BETWEEN the pair of lines |
| alternate exterior angles | pair of angles that are on OPPOSITE sides of the transversal and are on the OUTSIDE of the pair of lines |
| corresponding angles | the pair of angles that are in the same position on both of the pair of lines cut by the transfersal and are thus congruent |
| polygon | a plane figure that consists of line segments joining three or more points; end line called a side & each point called a vertice |
| triangle | formed when 3 points not on the same line are joined in pairs by line segments |
| acute triangle | triangle formed by 3 acute angles |
| equiangular triangle | triangle has 3 equal angles (each 60 degrees) |
| right angle | triangle has one right (90 degree) angle |
| obtuse angle | triangle has one obtuse angle |
| sum of angles in a triangle | 180 degrees |
| equilateral | triangle has 3 equal sides |
| isoceles | triangle has 2 equal sides (known as the "legs" |
| scalene | triangle has no sides equal |
