Question 1068872
Use the Pythagorean theorem,
{{{L^2=(L-8)^2+(L-4)^2}}}
{{{L^2=L^2-16L+64+L^2-8L+16}}}
{{{L^2=2L^2-24L+80}}}
{{{L^2-24L+80=0}}}
{{{(L-20)(L-4)=0}}}
Two potential answers but since one length requires subtracting 8, it would lead to a negative length which doesn't make sense.
{{{L-20=0}}}
{{{L=20}}}{{{ft}}}