Question 943060
first, write it in  the form {{{(x-h)^2 +(y-k)^2=r^2}}} then ({{{h}}},{{{k}}}) is the center and {{{r}}} is the radius

{{{y=sqrt (-12x-x^2)}}} ..... square both sides


{{{y^2=-12x-x^2}}}

{{{x^2+12x+y^2=0}}}

{{{(x^2+12x+_)-_+y^2=0 }}} complete square

{{{(x^2+12x+6^2)-36+y^2=0}}}

{{{(x+6)^2+y^2=36}}}

{{{(x+6)^2+(y-0)^2=6^2}}}

center ({{{-6}}},{{{0}}}) and radius of {{{r=6}}}


To sketch, plot the center. The radius is {{{r=6}}} so go out {{{6}}} units in each direction until you have enough points to draw in the graph, or use a compass.
few more points

({{{-12}}},{{{0}}})

({{{-6}}},{{{6}}})

({{{0}}},{{{6}}})


{{{drawing( 600, 600, -15, 10, -10, 10,
circle(-6,0,.2),locate(-6,0,C(-6,0)),circle(-12,0,.2),circle(-6,6,.2),circle(0,0,.2),
 graph( 600, 600, -15, 10, -10, 10, sqrt(-12x-x^2))) }}}