Circle A has a radius of 5 and a center of (2,7). Circle B has a radius of 4 and a center of (7,3). If circle B is translated by <1,2>, does it overlap circle A? If not, what is the minimum distance between points on both circles?

1 Answer
Jan 21, 2018

circles 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 centre of B under
under the given translation

under a translation <1,2>

(7,3)(71,3+2)(6,5)new centre of B

to calculate d use the distance formula

xd=(x2x1)2+(y2y1)2

let (x1,y1)=(2,7) and (x2,y2)=(6,5)

d=(62)2+(57)2=16+4=204.47

sum of radii =5+4=9

since sum of radii>d then circles overlap
graph{((x-2)^2+(y-7)^2-25)((x-6)^2+(y-5)^2-16)=0 [-20, 20, -10, 10]}