6.6 The Law of Cosines
Ideas in this lesson
- Law of Cosines: finding a side (SAS)
- Law of Cosines: finding an angle (SSS)
- Heron's Formula
- Choosing Law of Sines or Law of Cosines
Law of Cosines: finding a side (SAS) · Worked example
a = 3, b = 4, C = 90°. c?
Answer: 5
Pythagoras is a special case.