| A | B |
|---|
| circle | the set of all of the points in a plane equidistant from the center |
| circumference | the distance around a circle |
| ray | a set of an infinite # of points beginning at one definite point and extending out indefinitely |
| second | smallest unit a degree may be divided up into |
| arc | a segment of the circumference of a circle |
| bisect | to cut an angle exactly in half |
| diameter | distance across a circle through its center |
| congruent | equal or the same |
| vertex | common endpoint of an angle |
| minute | a degree has 60 of these |
| degree | the largest and most common unit of measure for an angle |
| radius | the distance from the encter of a circle to any point on the circle |
| right angle | measures exactly 90 degrees |
| acute angle | measures less than 90 degrees |
| obtuse angle | measures more than 90 degrees but less than 180 degrees |
| straight angle | measures exactly 180 degrees |
| angle | a union of two rays with a common endpoint |
| pi | a number often used with circles |
