1. Law of Cosines 9.4

2. What we know so far: Right Triangle: SOH CAH TOA Right Triangle: SOH CAH TOA Not a right triangle: SSA then we use Law of Sines But watch for the ambiguous case Not a right triangle: SSA then we use Law of Sines But watch for the ambiguous case What do we do if we know SSS or SAS??

3. Meet Professor Burger Prof Burger and Law of Cosines

4. Law of Cosines Use this when you know all the sides of a triangle (SSS) or you know 2 sides and an included angle (SAS).

5. A triangle has sides of 6, 12 and 15. Find the measure of the smallest angle.

6. In the same triangle of sides 6, 12 and 15, find the length of the median to the longest side.

7. A parallelogram has diagonals of length 20 and 12. If diagonals intersect to form a 60 degree angle, find the perimeter of the parallelogram.

8. Find the area of the quadrilateral with sides of length 6, 9, 12, 15. There is a 72 degree angle between the adjacent sides 6 and 15.

9. Homework: 9.4 page 352 2, 4, 10, 12-17