## anonymous one year ago given the center (h,k) and radius r=3, write an equation for the circle in standard form a) (x+5)^2+y^2=9 b) (x-5)^2+y^2=9 c) (x-5)^2+y^2=3

1. SolomonZelman

The equation of a circle is: $$\large\color{black}{ \displaystyle (x-{\rm \color{red}{h}} )^2+ (y-{\rm \color{blue}{k}} )^2 = {\rm \color{green}{r}}^2 }$$ Where 1) $$\large\color{black}{ \displaystyle({\rm \color{red}{h}} ,~{\rm \color{blue}{k}} )}$$ is the $$\normalsize\color{red}{ \bf c\color{blue}{e}n\color{blue}{t}e\color{blue}{r} }$$ of the circle. 2) $$\large\color{black}{ \displaystyle {\rm \color{green}{r}} }$$ is the $$\normalsize\color{green}{ \bf radius }$$ of the circle.

2. SolomonZelman

this is the general form, and you don't even need to change the (h,k). All you need to do is to substitute 3 for $$\rm \color{green}{r}$$.

3. SolomonZelman

you have some typos in a question apparently....

4. anonymous

its B ? i forgot to put that (h,k)=(5,0)

5. SolomonZelman

ok, h=5 k=0 r=3 then, yes, option B is correct. (x-5)²+y²=9

6. SolomonZelman

questions?

7. anonymous

no thank you !

8. SolomonZelman

Alright! You are welcome; have a good luck!