| A | B |
|---|
| acute angle | less than 90 degrees |
| right angle | exactly 90 degrees |
| obtuse angle | greater than 90 degrees |
| straight angle | exactly 180 degrees |
| complementary | two angles whose measures total exactly 90 degrees |
| supplementary | two angles whose measures total 180 degrees |
| adjacent angles | angles that are side by side (they share a ray) |
| vertical angles | opposite angles formed by intersecting lines-they are congruent |
| congruent angles | have exactly the same measures |
| plane | a flat surface that extends without end |
| parallel lines | lines in the same plane that never intersect (exactly the same distance apart at every point) |
| intersecting lines | lines that cross at one point |
| perpendicular lines | intersecting lines that form four right angles |
| corresponding angles | angles that occupy the same position when a line intersects two other lines |
| acute triangle | triangle with three acute angles |
| right triangle | triangle with one right angle |
| obtuse triangle | triangle with one obtuse angle |
| equilateral triangle | triangle with three congruent sides |
| isosceles triangle | triangle with two congruent sides |
| scalene triangle | triangle with no congruent sides |
