2. CCSS G-CO 9: Prove theorems about lines and angles. G-CO 10: Prove theorems about triangles. G-CO 11: Prove theorems about parallelograms. Lesson Goals  Identify, name, and describe polygons. ESLRs: Becoming Effective Communicators, Competent Learners and Complex Thinkers

3. a 2-dimensional plane figure Formed by three or more line segments called sides Adjacent sides are non-collinear Each side intersects exactly 2 other sides at their endpoints

4. polygon MNOPQR polygons are named using the vertices in consecutive order

5. yes no Which of the shapes are polygons?

6. triangle quadrilateral pentagon hexagon heptagon octagon

7. nonagon decagon dodecagon n-gon

8. Convex No line that contains a side passes through the interior of the polygon interior

9. Convex All vertices “point” outward.

10. Convex No line that contains a side passes through the interior of the polygon Concave A polygon that is not convex interior

11. Concave At least one vertex “points” inward.

12. Not a polygon Some sides are not line segments Is the figure a polygon? If it is, state whether it is convex or concave.

13. Classify by number of sides. octagon

14. Convex or Concave? concave

15. Classify by number of sides. dodecagon

16. Convex or Concave? convex

17. Classify by number of sides. heptagon

18. Convex or Concave? concave

19. Equilateral: all sides congruent Equiangular: all angles congruent Regular: equilateral and equiangular

20. State whether the polygon is best described as equilateral, Equiangular, regular, or none of these? regular equilateral equilangular

21. The sum of the measures of the interior angles of a convex polygon is where n is the number of sides. 1 2 3 4

22. Find the sum of the measures of the interior angles of a convex decagon.

23. Find x.

25. Find the value of x.

26. Find the measure of each interior angle. Is the quadrilateral regular? D B C A Not regular

27. A polygon is __________________. A polygon is classified by _________, _________, or ________. A regular polygon has _____________. The Polygon Interior Angle Sum Theorem says ____________.

28. p. 325: 1, 2, 4 – 9, 18 - 20, 27 – 32, 41 – 45 o p. 665: 3, 4, 7, 13, 15, 20, 49