Law of Cosines Derivation/Proof

Law of Cosines Derivation/Proof

A quick derivation of the Law of Cosines, using the Pythagorean Theorem (see my video on this:    • Pythagorean Theorem Derivation/Proof  ) & Pythagorean Identity (see my video on this:    • Pythagorean Identity Derivation/Proof  )