Circle A has a center at #(3 ,5 )# and a radius of #1 #. Circle B has a center at #(-2 ,1 )# and a radius of #3 #. Do the circles overlap? If not, what is the smallest distance between them?

1 Answer
Jul 27, 2016

The circles do not overlap.
There is a minimum distance of (approximately) #2.4# between them.

Explanation:

The length of the line segment between A at #(3,5)# and B at #(-2,1)# is given by the Pythagorean Theorem as
#color(white)("XXX")L_(AB)=sqrt((3-(-2))^2+(5-1)^2)#
#color(white)("XXXXXX") = sqrt(41)#
#color(white)("XXXXXX")~~6.4#

The radius of A covers #1# unit of this length
and the radius of B covers another #3# units
for a total of #4# units covered by one or the other of the circles.

This leaves #6.4-4=2.4# units uncovered
and this is the minimum distance between the two circles.