Cosine Formula
In any triangle ABC,
a2 = b2 + c2 − 2bc cosA
b2 = c2 + a2 − 2ca cosB
c2 = a2 + b2 − 2ab cosC
These are called cosine formulae.
In any triangle ABC,
a2 = b2 + c2 − 2bc cosA
b2 = c2 + a2 − 2ca cosB
c2 = a2 + b2 − 2ab cosC
These are called cosine formulae.