Question 990952
x, y, z, the sides;
{{{x+y+z=56}}}
Take z as the longest side; {{{z=-2+x+y}}};
Take x as the shortest side; {{{x=-13+z}}};



This makes a system of equations
{{{system(x+y+z=56,x=z-13,z=x+y-2)}}}


Maybe Row Elimination would be the way to go.  Another way is substitute for x in the first and third equations, and continue to work the the two-variable system resulting.  Doing this way:


{{{system(z-13+y+z=56,z=z-13+y-2)}}}


{{{system(2z+y=56+13,0=y-15)}}}


{{{system(2z+y=69,y=15)}}}


Found one side length, {{{highlight(y=15)}}}.


{{{2z+15=69}}}
{{{2z=69-15}}}
{{{2z=74}}}
{{{highlight(z=37)}}}