Answer
7.2 feet
Work Step by Step
$20^2=(x+8)^2+x^2$
$400=(x+8)(x+8)+x^2$
$400=x*x+x*8+x*8+8*8+x^2$
$400=x^2+8x+8x+64+x^2$
$400=2x^2+16x+64$
$400-400=2x^2+16x+64-400$
$2x^2+16x-336=0$
$a=2$, $b=16$, $c=-336$
$x=(-b±\sqrt {b^2-4ac})/2a$
$x=(-16±\sqrt {16^2-4*2*-336})/2*2$
$x=(-16±\sqrt {256+2688})/4$
$x=(-16±\sqrt {2944})/4$
$x=(-16±54.258)/4$
$x=(-16+54.258)/4$
$x=38.258/4$
$x=9.5645$
$x=(-16-54.258)/4$
$x=-70.258/4$
$x=-17.5645$
This answer isn’t valid since we are talking about distance, and we can’t have a negative distance.
$x=9.5645$
$x+(x+8)-20$
$2x+8-20$
$2x-12$
$2*9.5645-12$
$19.129-12$
$7.129$
$7.13$
7.2 feet
