Circle A has a radius of 2 and a center of (6,5). Circle B has a radius of 3 and a center of (2,4). If circle B is translated by <1,1>, does it overlap circle A? If not, what is the minimum distance between points on both circles?

2 Answers
May 14, 2018

circles overlap

Explanation:

what we have to do here is compare the distance (d)
between the centres 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 new centre
of B after the given translation

under the translation <1,1>

(2,4)(2+1,4+1)(3,5)new centre of B

to calculate d use the distance formula

d=(x2x1)2+(y2y1)2

let (x1,y1)=(6,5) and (x2,y2)=(3,5)

d=(36)2+(55)2=9=3

sum of radii =2+3=5

since sum of radii>d then circles overlap
graph{((x-6)^2+(y-5)^2-4)((x-3)^2+(y-5)^2-9)=0 [-20, 20, -10, 10]}

May 14, 2018

The distance between the centers is 3, which satisfies the triangle inequality with the two radii of 2 and 3, so we have overlapping circles.

Explanation:

I thought I did this one already.

A is (6,5) radius 2

B's new center is (2,4)+<1,1>=(3,5), radius still 3

Distance between centers,

d=(63)2+(55)2=3

Since the distance between the centers is less than the sum of the two radii, we have overlapping circles.