| A | B |
|---|
| point | an exact position on a shape often marked by a dot |
| line | a straight path that is endless in both directions |
| line segment | part of a line with two endpoints |
| ray | part of a line that begins at a point and is endless in one direction |
| endpoint | a point at the end of a ray or line segment |
| vertex | the point that two rays of an angle have in common |
| parallel lines | lines that do not cross |
| intersecting lines | lines that cross at a point |
| perpendicular lines | lines that intersect and form right or 90 degree angles |
| protractor | a tool used to measure the size of an angle |
| degree | the unit of measurement for angles |
| right angle | an angle measuring exactly 90 degrees formed by perpendicular lines |
| acute angle | an angle measuring less than 90 degrees |
| obtuse angle | an angle measuring more than 90 degrees |
| polygon | a closed figure made of line segments |
| equilateral triangle | a triangle with 3 equal sides |
| isosceles triangle | a triangle with at least 2 equal sides |
| scalene triangle | a triangle with no equal sides |
| right triangle | a triangle with one right angle |
| acute triangle | a triangle with 3 acute angles |
| obtuse triangle | a triangle with 1 obtuse angle |
| quadrilateral | a polygon with 4 sides and 4 angles |
| square | a quadrilateral with 4 equal sides and 4 right angles |
| rectangle | a quadrilateral with 4 right angles and opposite parallel sides the same length |
| parallelogram | a quadrilateral with two pairs of parallel sides |
| rhombus | a quadrilateral with two pairs of parallel sides and all sides are equal length |
| trapezoid | a quadrilateral with only one pair of parallel sides |
