Re: HSC 2015 4U Marathon - Advanced Level
The proof looks solid, well done
Here was my approach:
\\ $Let$ \ x = b+c-a, y = a+c - b, z = a+b-c
\\ $Since$ \ a,b,c \ $are sides of a triangle$ \ x,y,z \ $are all non-negative$
\\ c = \frac{x+y}{2} , b = \frac{x+z}{2} , a = \frac{y+z}{2}
\\...