Just a quick question- when is the Law of Cosines c2=a2+b2+2abcos(C)? I thought it was if the triangle you were using the Law of Cosines on was obtuse, but I'm confused because when I browse on the internet it says it always is c2=a2+b2−2abcos(C)
+1252 It is always with -2ab*cos(C). When C is obtuse, then cos(C) is negative and so -2ab*cos(C) is positive.
You are very welcome!
:P
