How to graph a circle given the equation in standard form

x^2 + y^2 = 1

[trixieisabelina]

Very helpful to the student like me thankyou sir.

[jerwintermos]

Sir pls help me what if the radius becomes 0? how can i graph it? this is the general form x²+y²-4x-8y+20=0 the radius becomes 0 when i convert it to standard form

[ramnganingjelly]

will there be a solution for the equation
x^2+y^2=-1 where x^2 & y^2 are real valued functions....????