| A | B |
|---|
| complementary angles | add up to 90 degrees |
| supplementary angles | add up to 180 degress |
| adjacent angles | share a common side |
| vertical angles | share a vertex and one side but no interior points |
| acute angle | less than 90 degrees |
| obtuse angle | greater than 90 but less than 180 degrees |
| right angle | 90 degrees |
| straight angle | 180 degrees |
| obtuse triangle | has one obtuse angle |
| acute triangle | has all acute angles |
| right triangle | has one 90 degree angle |
| scalene triangle | no sides congruent |
| isosceles triangle | 2 sides and 2 angles congruent |
| equilateral triangle | all sides and all angles congruent |
| congruent triangles | triangles whose corresponding parts are congruent |
| trapezoid | has exactly one pair of parallel sides |
| parallelogram | has both pairs of sides parallel |
| rectangle | a parallelogram with four right angles |
| rhombus | a parallelogram with four congruent sides |
| square | a parallelogram with four right angles AND four congruent sides |
| triangle | a polygon with 3 sides |
| quadrilateral | a polygon with 4 sides |
| pentagon | a polygon with 5 sides |
| hexagon | a polygon with 6 sides |
| octagon | a polygon with 8 sides |
| decagon | a polygon with 10 sides |
