Question

I am so use to A^2+B^2=C^2. I never seen this problem in my life :P

Answer 1

This problems emerges from the study of cosine rule,
\(C^2=A^2+B^2-2AB~cos(C)\)
When C is acute, cos(C)>0, when C is obtuse, cos(C)<0,and finally
when \(C=90^\circ \), cos(C)=0 and the equation becomes Pythagoras theorem.