Two circles have the following equations: (x -1 )^2+(y -4 )^2= 9 and (x +6 )^2+(y +9 )^2= 25 . Does one circle contain the other? If not, what is the greatest possible distance between a point on one circle and another point on the other?

1 Answer
Jan 30, 2017

The two circles are external one another and the greatest possible distance is sqrt 218-8

Explanation:

The first circle (A) have the centre in Xca=1 nd Yca=4, and its radius is 3.
the second circle (B) has the centre in Xcb=-6 and Ycb=-9. Its radius is 5.
the distance between the centres is:

d=sqrt ((Xca-XCb)^2 +(Yca-YCb)^2
d=sqrt (49+169)=sqrt 218
the sum of the radii is 3+5 =8 < sqrt 218
The two circles are external one another and the greatest possible distance is sqrt 218-8