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 #color(blue)"compare "# the distance (d) between the centres of the circles to the #color(blue)"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)to(1+2,7+4)to(3,11)larrcolor(blue)"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"#

#rArrd=11-3=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]}