Lesson Vocabulary

• Law of Cosines

Take Note Theorem: Law of Cosines

In Δ ABC , cap delta let a, b, and c represent the lengths of the sides opposite ∠ A , ∠ B , angle eh comma angle b comma and ∠ C , angle c comma respectively.

• a 2 = b 2 + c 2 − 2 b c cos A eh squared , equals , b squared , plus , c squared , minus 2 b c cosine eh
• b 2 = a 2 + c 2 − 2 a c cos B b squared , equals , eh squared , plus , c squared , minus 2 eh c cosine b
• c 2 = a 2 + b 2 − 2 a b cos C c squared , equals , eh squared , plus , b squared , minus 2 eh b cosine c