Write the equation of the circle with center (-6, -4) and containing the point (-2, -1).

Question

amistre64 · Answer

given a center point (a,b)

(x-a)^2+(y-b)^2 = r^2

such that r is the distance between the center and the given point

anonymous · Answer

What do I do with the contained point (-2,-1)?

amistre64 · Answer

that helps to define the radius of your circle

the distance from the center to that point ....

amistre64 · Answer

do you recall how to find the distance between 2 points?

anonymous · Answer

yes by using the distance formula which is$$\sqrt{(x2-x1)^2+(y2-y1)^2}$$

amistre64 · Answer

correct

anonymous · Answer

so i take both the contained point and the center and plug it in ti that equation?

amistre64 · Answer

well, seeing that we need to define the distance between them; and that is the formula for finding the distance between 2 points ... im going with yes :)

anonymous · Answer

Wonderful

amistre64 · Answer

the formula is nice but i tend to place things in the wrong spots .... so i just step thru it

subtract the points

 (-6, -4) 
-(-2, -1)
--------
  -4, -3

squre that parts:  16, 9

add them:  16+9 = 25

and sqrt:  sqrt(25) = 5

anonymous · Answer

So after substituting the two points into the distance formula i get a radius of 5.385164807

amistre64 · Answer

lets go with 5

anonymous · Answer

which then squared equals 29

anonymous · Answer

Or we could do 5...

amistre64 · Answer

putting it all together we should get
$$(x+6)^2+(y+4)^2=25$$

anonymous · Answer

That is what I got!

amistre64 · Answer

yay!!

anonymous · Answer

Thanks for your help my friend.

amistre64 · Answer

youre welcome