abcbcacab=a+b+cbca+b+ccaa+b+cab=(a+b+c)1bc1ca1ab=(a+b+c)0b−cc−a0c−aa−b1ab=(a+b+c)[ab+bc+ca−a2−b2−c2]=−(a+b+c)[(a−b)2+(b−c)2+(c−a)2] Since a,b,c are sides of a scalene triangle, therefore at least two of the a,b,c will be unequal. ∴∴(a−b)2+(b−c)2+(c−a)2>0 Also a+b+c>0−(a+b+c)[(a−b)2+(b−c)2+(c−a)2]<0