| A | B |
|---|
| perpendicular lines | two lines that form right angles where they intersect |
| line segment | a part of a line that has two end points |
| equilateral triangle | a triangle with three equal sides |
| isosceles triangle | a triangle that has at least two equal sides |
| scalene triangle | a triangle with no sides the same length |
| right triangle | a triangle that has one right angle |
| acute angle | an angle that has a measure less than 90 degrees |
| obtuse angle | an angle with a measure greater than 90 degrees |
| protractor | an instrument used to measure the size of an angle |
| chord | a line segment with both end points on a circle |
| circle | a plane figure in which all the points are the same distance from the center |
| diameter | a line segment that goes from one point on a circle through the center to another point on the circle |
| hexagon | a polygon with six sides |
| intersecting lines | lines that cross at a point |
| octagon | a polygon with eight sides |
| parallel lines | lines that lie in the same plane and do not intersect |
| parallelogram | a quadrilateral with two pairs of opposite parallel sides |
| pentagon | a polygon with five sides |
| point | an exact position often marked by a dot |
| polygon | a closed plane figure made up of line segments |
| quadrilateral | a polygon with four sides |
| radius | a line segment from the center of a circle to any point on the circle |
| ray | part of a line that begins at a point and is endless in one direction |
| rectangle | a quadrilateral with four right angles and opposite sides parallel and the same length |
| rhombus | a quadrilateral with two pairs of parallel sides and all sides the same length |
| right angle | an angle that has a measure of 90 degrees |
| line | a straight path that is endless in both directions |
| square | a quadrilateral that has four equal sides and four right angles |
| trapezoid | a quadrilateral that has exactly one pair of parallel sides |
| vertex | the point that two or more edges meet |
