The equation of a circle is (x - 4)2 + (y + 1)2 = 9. Which graph best represents the circle?

Question

anonymous · Answer

A circle of Radius 3, with the Center at M(4/-1)

zeesbrat3 · Answer

thanks so much. Do you think you can help me with another?

anonymous · Answer

(-: Lets see, what's the question?

zeesbrat3 · Answer

Look at the graph.

Which equation best represents the circle in the graph?

anonymous · Answer

Well, judging by my sight, M is M(-1/2)

anonymous · Answer

The Radius is 5

zeesbrat3 · Answer

so its either c or d

zeesbrat3 · Answer

no its d

anonymous · Answer

so it should be
$$ f(x,y)= (x+1)^2+(y-2)^2=25$$

zeesbrat3 · Answer

got them switched... its a

anonymous · Answer

ok, well this is the equation of the circle above.

zeesbrat3 · Answer

thanks. How do you find the equations?

anonymous · Answer

the general solution of a circle looks like this

$$ \large f(x,y)=(x-u)^2+(y-v)^2=r^2$$

anonymous · Answer

where $ u, v$ are the coordinates of the center.

anonymous · Answer

r = the radius, but it's always squared, so when you have 25, your radius is 5, when you have 9, your actual radius is 3, and so on and so forth.

zeesbrat3 · Answer

Okay, thanks so much!

anonymous · Answer

very welcome