1. Law of Cosines
Advanced Math 8.2

2. Proof
Advanced Math 8.2

3. Law of Cosines
Standard form – use for SAS
Advanced Math 8.2

4. Law of Cosines
Alternative form – use for SSS
Advanced Math 8.2

5. Example If a = 3.7 m, c = 6.4 m, and B = 23°, find b.
Advanced Math 8.2

6. Example
If a = 51 cm, b = 24 cm, and c = 31 cm, find the largest angle.
Advanced Math 8.2

7. Example
If b = 63.4 km, c = 75.2 km, and A = 124°40´, solve the triangle.
Advanced Math 8.2

8. Example If a = 8 cm, b = 3 cm, and c = 9 cm, solve the triangle.
Advanced Math 8.2

9. Heron’s formula
See page 653
Advanced Math 8.2

10. Example
If a = 48 yd, b = 75 yd, and c = 63 yd, find the area of the triangle.
Advanced Math 8.2

11. Example
If a = 12 m, b = 15 m, and c = 9 m, find the area of the triangle.
Advanced Math 8.2

12. Example
You want to buy a triangular lot measuring 1350 ft by 1860 feet by 2490 ft. The price of land is $2200 per acre. How much does the land cost? (1 acre = ft2)
Advanced Math 8.2