| A | B |
|---|
| angle | two rays with a common endpoint |
| acute angle | angle measuring less than 90 degrees |
| obtuse angle | angle measuring more than 90 degrees |
| right angle | angle measuring 90 degrees |
| straight angle | angle that measures 180 degrees |
| adjacent angles | share a vertex and one side |
| complementary angles | the sum of the measures of two angles is 90 degrees |
| supplementary angles | the sum of the measures of two angles is 180 degrees |
| scalene triangle | no congruent sides |
| isosceles triangle | at least two congruent sides |
| equilateral triangle | three congruent sides |
| right triangle | one right angle |
| acute triangle | three acute angles |
| obtuse triangle | one obtuse angle |
| parallel lines | lie in the same plane but do not intersect |
| trapezoid | exactly one pair of parallel sides |
| parallelogram | both pairs of opposite sides parallel |
| rectangle | a parallelogram with 4 right angles |
| rhombus | parallelogram with 4 congruent sides |
| square | parallelogram with 4 right angles & 4 congruent sides |
| regular polygon | all sides congruent and all sides congruent |
| circle | set of points in a plane that are all the same distance from the center |
| radius | segment that has one endpoint at the center and the other endpoint on the circle |
| diameter | segment that passes through the center of a circle with both endpoints on the circle |
| central angle | an angle with its vertex at the center of a circle |
| chord | segment that has both endpoints on the circle |
| arc | part of a circle |
| semicircle | half a circle |
| compass | geometric tool used to draw circles and arcs |
| inscribed polygon | polygon whose sides are chords of a circle |
| perpendicular lines | lines that intersect to form right angles |
| perpendicular bisector | a line that is perpendicular to a segment at its midpoint |
| segment bisector | aline that goes through the midpoint of the segment |
