Question 203859
If {{{y}}} is the end of the stick leaning against the wall, and
{{{x}}} is the end of the stick on the ground, then
{{{m = sqrt(x^2 + y^2)/2}}} is the formula for the midpoint of the stick

{{{m^2 = (x^2 + y^2) / 4}}}
{{{x^2 + y^2 = 4m^2}}}
{{{y^2 = 4m^2 - x^2}}}
{{{y = sqrt(4 m^2 - x^2)}}}
I'll make {{{m}}}= a constant,
{{{m = 1}}} and {{{m = 1/2}}} and I'll plot them 
{{{ graph( 400, 400, -3, 3, -3, 3, sqrt(4 - x^2) , sqrt(1 - x^2))}}}
The plot of {{{m}}} is a semicircle. You can pick either the 
1st or 2nd quadrant.