| A | B |
|---|
| plane | a flat surface that extends forever |
| ray | a part of a line that starts at one endpoint and extends forever |
| segment | a part of a line between two endpoints |
| angle | a figure formed by two rays with a common endpoint called a vertex |
| right angle | an angle that measures 90 degrees |
| acute angle | an angle that measure less than 90 degrees |
| obtuse angle | an angle that measures more than 90 degrees |
| point | an exact location in space |
| line | a straight path that extends without end in opposite directions |
| congruent | having the same size and shape |
| vertical angles | a pair of opposite congruent angles that are formed by intersecting lines |
| parallel lines | lines in a plane that do not intersect |
| perpendicular lines | lines that intersect to form right angles |
| transversal | a line that intersects two or more lines |
| Triangle Sum Theorem | the theorem that states that the measures of the angles in a triangle add up to 180 degrees |
| acute triangle | a triangle with all the angles measuring less than 90 degrees |
| equilateral triangle | a triangle with three congruent sides |
| isosceles triangle | a triangle with at least two congruent sides |
| obtuse triangle | a triangle containing one obtuse angle |
| right triangle | a triangle containing a right angle |
| scalene triangle | a triangle with no congruent sides |
| polygon | a closed plane figure formed by three or more line segments that intersect only at their endpoints (vertices) |
| regular polygon | a polygon with congruent sides and angles |
| trapezoid | a quadrilateral with exactly one pair of parallel sides |
| parallelogram | a quadrilateral with two pairs of parallel sides |
| rectangle | a parallelogram with four right angles |
| rhombus | a parallelogram with all sides congruent |
| square | a rectangle with four congruent sides |
| slope | a measure of the steepness of a line on a graph |
| rise | the vertical change when the slope of a line is expressed as "rise over run" |
| run | the horizontal change when the slope of a line is expressed as "rise over run" |
