Question 641735
{{{x^2+y^2=64}}}

{{{y^2=-x^2+64}}}

{{{y=+-sqrt(-x^2+64)}}}

if {{{x=0}}}...=>...{{{y=8}}} or {{{y=-8}}}

if {{{y=0}}}...=>...{{{x=8}}} or {{{x=-8}}}

{{{ graph( 600, 600, -10, 10, -10, 10, sqrt(64-x^2),-sqrt(64-x^2)) }}}

so, your answer is: {{{ circle}}}