1. Welcome to Geometry! Learning Target: I will calculate the area of ANY regular polygon! Welcome to Geometry! 1. Sit in your assigned seat. 2. Write down your learning target. 3.Silently start your warm-up for today. (An SAT problem! ) Two sides of an isosceles triangle are 20 and 30. What is the difference of the largest and the smallest possible perimeters?

2. 1.Sit in your assigned seat. 2.Write down your learning target. 3.Silently work on your warm-up. Learning Target: You have 5 minutes

3. 1.Sit in your assigned seat. 2.Write down your learning target. 3.Silently work on your warm-up. You have 4 minutes

4. You have 3 minutes 1.Sit in your assigned seat. 2.Write down your learning target. 3.Silently work on your warm-up.

5. You have 2 minutes 1.Sit in your assigned seat. 2.Write down your learning target. 3.Silently work on your warm-up.

6. You have 1 minutes 1.Sit in your assigned seat. 2.Write down your learning target. 3.Silently work on your warm-up.

7. Time’s Up! 1. Pencils Down 2. Body Forward 3. Eyes on Ms. Chui 4. Mouth Closed Ready for Success! Learning Target: I will calculate the area of ANY regular polygon!

9. FLO meetings today: BlueStamp EngineeringHoustonEngineering Thursday, Feb 20th (Lunch at 12:00, After School at 4:30) G.R.A.D.E. The University of HoustonEngineering Thursday, Feb 20th (Lunch at 12:00, After School at 4:30)

11. Deadline to apply: March 7 th, 2014

12. INTERESTED?? Go to the CCC during lunch and/or after school!

13. If you’re applying to programs & need help with essays, don’t be afraid to ask!

14. Yesterday… Naviance Quiz on Edmodo Please complete!! Can’t log in to Naviance? Email Ms. Doan

15. Today’s objective… How would I find the area of this shape??

16. Use what we have learned to come up with some ideas.

17. The method we are learning today works for ANY regular polygon

18. X out the NON polygons!

19. X X X X X

20. Polygon definition: __________________ Closed figure with straight sides

21. X out the IRREGULAR polygons! X XX X X X

22. All sides and all angles the same Regular polygon definition: __________________

23. Switch

24. Review: How do you find the area of a rectangle? A = bh or A = lw

25. Parallelograms are awesome What would happen if I cut a triangle off of one end of the parallelogram and translated it to the other side? What shape have we formed? So how do you find the area? A = lw or A = bh

26. Review: How do you find the area of a triangle? A = ½ bh or A = bh/2

27. Review: How do you find the area of a circle? A = π r 2

28. How about a pentagon? What if we cut the pentagon into congruent triangles? If you know the height of the triangle, you can find the area. So does the formula from the formula chart for a regular polygon make sense? A = ½ aP (A = ½ the apothem times the Perimeter) The height of one of those triangles would be perpendicular to the base and go right to the middle of the pentagon. That’s what we call the “apothem” of the polygon 18.2 cm If it is a regular pentagon, it’s easy. 12.5 cm A = ½ (b) (h) so A = ½ (18.2) (12.5) The area of one of the triangles is 113.75 cm 2 How many triangles are there?

30. 1212 a P _ apothem perimeter Add up all the sides!!

31. center regular polygon midpoint perpendicular (90°) | | | | The apothem is a PERPENDICULAR BISECTOR!

32. | | | | CORNER/VERTICES SIDE

33. Radius or apothem?

38. Now for an example problem:

39. A = ½ a P 5.1 P = 7.5 * 5 P = 37.5 37.5 A = ½ a P A = ½ * 5.1 * 37.5 A = 95.625 A = 95.63 units 2

40. ≈2.31

41. Practice makes Permanent! Finished early? Go to mschuigeometry.weebly.com Click on Lessons Scroll down to Thursday Click on Extended Practice Read the first page

42. Your HW is on the website!

44. This week, did I…  Treat everyone with respect?  Work with grit and persevere through problems?  Remain optimistic through challenges?  Improve my critical thinking and problem solving skills?  Take pride in all my work?  Seek out opportunities for improvement?