1. Plane figure A two dimensional figure. Chapter 10

2. polygon A closed plane figure of 3 or more line segments. They can have a different number of sides and angles. Chapter 10

3. triangle A 3 sided polygon with 3 angles. Chapter 10

4. quadrilateral A 4 sided polygon with 4 angles. Chapter 10

5. pentagon A 5 sided polygon with 5 angles. Chapter 10

6. hexagon A 6 sided polygon with 6 angles. Chapter 10

7. octagon An 8 sided polygon with 8 angles. Chapter 10

8. perimeter The distance around the outside of an object or shape. Chapter 10

9. area The number of square units needed to cover a plane figure without overlapping. Chapter 10

10. equilateral triangle A triangle with 3 equal sides. Chapter 10

11. isosceles triangle A triangle with 2 equal sides. Chapter 10

12. scalene triangle A triangle with NO equal sides. Chapter 10

13. right triangle A triangle with one right angle. Chapter 10

14. obtuse angle Angle bigger than 90 Chapter 10

15. acute angle Angle smaller than 90 Chapter 10

16. parallel Lines that are the same distance apart. Parallel lines do not meet. Chapter 10

17. rectangle Opposite sides are same length and are parallel. It also has 4 right angles. Chapter 10

18. rectangular solid A 3-dimensional figure with six faces that are rectangles. Chapter 10

19. square 4 sided that are the same length, opposite sides are parallel, has 4 right angles. Chapter 10

20. parallelogram Opposite sides are the same length and are parallel. Chapter 10

21. cube A 3-dimensional figure with 6 congruent square faces. Chapter 10

22. cone 3-dimensional figure with a curved surface and a circular base which comes to a point called the vertex. Chapter 10

23. pyramid A 3-dimensional figure with 5 faces. Chapter 10

24. cylinder A 3-dimensional figure having two circular bases and a curved surface connecting the two bases. Chapter 10

25. sphere A 3-dimensional figure that has the shape of a round ball. Chapter 10

26. volume The number of cubic units needed to fill a 3-dimensional figure or solid figure. Chapter 10

27. cubic unit A unit for measuring volume, such as a cubic inch or a cubic centimeter. Chapter 10