How do you use the law of cosines to show that for any triangle ABC, c^2<a^2+b^2 if C is acute and c^2>a^2+b^2 if C is obtuse?
1 Answer
Jan 6, 2017
Please see below.
Explanation:
According to cosine formula, in a triangle
Now if
i.e.
and hence
and if
i.e.
and hence