1. Honors Precalculus April 16, 2018 Mr. Agnew
The Law of Cosines
Honors Precalculus
April 16, 2018
Mr. Agnew

2. Essential Stuff Essential Question Essential Vocabulary
How do you find the missing sides and angles of a triangle?
Essential Vocabulary
Law of Sines
Law of Cosines
Right Triangle Trigonometry

3. What’s the Problem? Solve using the Law of Sines. A D 1. 2. 23 8 11
51° C O T 42 17 G

4. Law of Cosines

5. The Law of Cosines Use Law of Cosines with SAS and SSS.
What if given angle is right angle?
Pythagorean Theorem is a special case of the Law of Cosines.
Guided Practice
Sample Problems Worksheet

6. Heron’s Formula
If three sides of a triangle are known, we can use Heron’s Formula to find the area of that triangle:
s = ½ (a + b + c)
Examples

7. Homework: 4/16/18
Page 535 – 537 # 19, 29, 33, 37, 39, 43, 45, 47, 51, 53 Page 541 #7, 11, 17, 37, 41