1. Good Morning, Precalculus! To prepare for class: 1. Please find your DO NOW sheet and start today's DO NOW! 2. Take out your homework: worksheet 5-6 Do Now: Draw a triangle for which you would need the formula below to find the area: TRY NOT TO USE YOUR NOTES

2. Do Now: Draw a triangle for which you would need the formula below to find the area:

3. Upcoming Assignments Due Tuesday 3/19: Worksheet 5-6, questions 1-4 (find the missing side lengths and angles) Your Unit 10 Test will be next Tuesday, March 26!

4. HW Review Worksheet 5-6

5. HW Review Worksheet 5-6

6. HW Review Worksheet 5-6

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8. Unit 10, Obj.2 Grade: 12 Subject: Precalculus Date: 3/4/2013

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14. Turn OFF your SMART Response clicker!

15. Today's Agenda: 1. Do Now 2. HW Review 3. Unit 10, Obj. 2 Exit Slip 4. Today's Objective 5. Hero's Formula

16. Today's Objective Unit 10, Objective 3: I will be able to calculate the area of a triangle using Hero's (Heron's) Formula. Section 7-4, pgs. 448-455

17. Hero's Law

18. Hero's Law: New Vocab Semiperimeter: In a polygon, the semiperimeter is half of the perimeter.

19. Using the law of sines, we were able to find the area of a triangle when: 1. We knew two sides and their included angle 2. We knew at least two of the angles and one of the sides. Now, we can find the area of a triangle when we only know the lengths of all three sides. To do this: 1. Find the semiperimeter using the formula s = 1 (a+b+c), where a, b, and c are the lengths of the three sides. 2. Then, use Hero's Law:k = √s(s-a)(s-b)(s-c), where s is the semiperimeter of the triangle and a, b, and c are the lengths of the three sides. Hero's Law 2 A B C a b c

24. Work alone or with a partner to complete "More practice!"