Graphics[{Line[{{-1,0},{0,.7},{1,0},{-1,0}}],Text[Style["A",16],{-1.1,0}], Text[Style["B",16],{0,.8}], Text[Style["C",16],{1.1,0}
], ImageSize->80}]

Graphics[{Lighter[Lighter[Orange]],Disk[{0,1},5],Black,PointSize[0.03],Point[{0,1}]},Axes->True,ImageSize->200]

Solve[x^2+(y-1)^2==5^2,{y}]

lc[x_]:=1-Sqrt[25-x^2]

uc[x_]:=1+Sqrt[25-x^2]

{lc[x],uc[x]}

Plot[lc[x],{x,-5,5},AxesOrigin->{0,0},AspectRatio->1/2]

Plot[{lc[x],uc[x]},{x,-5,5},PlotRange->7,AxesOrigin->{0,0},AspectRatio->7/5]