Question 177735
{{{A=sqrt(s(s-a)(s-b)(s-c))}}} Start with Hero's formula



{{{A=sqrt(6(6-5)(6-12)(6-5))}}} Plug in {{{a=5}}}, {{{b=12}}}, {{{c=5}}} and {{{s=6}}}



{{{A=sqrt(6(1)(-6)(1))}}} Subtract



{{{A=sqrt(-36)}}} Multiply



Since you CANNOT take the square root of a negative number, this means that a triangle CANNOT be formed given side lengths of 5, 12, and 5 inches. So double check the problem.