| A | B |
|---|
| line | a straight path that goes on forever in both directions |
| ray | part of a line having only one endpoint |
| angle | two rays having the same endpoint |
| vertex | the point that two rays of an angle have in common |
| protractor | an instrument used to measure the size of an angle |
| degree | a unit of measure for angles |
| polygon | a plane, closed figure formed by line segments |
| line segment | a part of a line that has two end points |
| quadrilateral | a polygon with four sides |
| similar polygons | polygons that have the same shape |
| congruent polygons | polygons that have the same size and shape |
| pentomino | a figure made of five congruent squares joined edge to edge |
| line of symmetry | a line on which a figure can be folded so that the two parts fit exactly |
| acute angle | an angle whose measure is less than 90 degrees |
| right angle | an angle whose measure is 90 degrees |
| obtuse angle | an angle whose measure is greater than 90 degrees |
| straight angle | an angle whose measure is 180 degrees |
| equilateral triangle | a triangle with all sides the same length |
| isosceles triangle | a triangle with two sides the same length |
| scalene triangle | a triangle with no sides the same length |
| right triangle | a triangle with one right angle |
| acute triangle | a triangle with all angles less than 90 degrees |
| obtuse triangle | a triangle with one angle greater than 90 degrees |
| square | all side the same length, four right angles |
| rectangle | opposite sides parallel and the same length, four right angles |
| parallelogram | two paris of parallel sides |
| rhombus | two pairs of parallel sides, all sides the same length, opposite angles equal |
| trapezoid | only one pair of parallel sides |
| motions | slide, flip,turn |
