Circle A has a radius of 1 and a center at (3,3). Circle B has a radius of 3 and a center at (1,7). If circle B is translated by <2,4>, does it overlap circle A? If not, what is the minimum distance between points on both circles?

1 Answer
Nov 5, 2017

no overlap

Explanation:

What we have to do here is compare the distance (d) between the centres of the circles to the sum of the radii

if sum of radii>d then circles overlap

if sum of radii<d then no overlap

before calculating d we require to find the coordinates
of the centre of circle B under the given translation
which does not change the shape of the circle only
it's position

under the translation <2,4>

(1,7)(1+2,7+4)(3,11)new centre of B

note that the coordinates of the 2 centres have the same
x-coordinate and so lie on the vertical line x=3

Hence d is the difference in the y-coordinates

d=113=8

sum of radii =1+3=4

since sum of radii<d then no overlap of circles
graph{((x-3)^2+(y-3)^2-1)((x-3)^2+(y-11)^2-9)=0 [-40, 40, -20, 20]}