Circle A has a radius of 5 5 and a center of (2 ,7 )(2,7). Circle B has a radius of 4 4 and a center of (7 ,3 )(7,3). If circle B is translated by <-1 ,2 ><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"circles overlap

Explanation:

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

• " if sum of radii ">d" then circles overlap" if sum of radii >d then circles overlap

• " if sum of radii"< d" then no overlap" if sum of radii<d then no overlap

"before calculating d we require to find the centre of B under"before calculating d we require to find the centre of B under
"under the given translation"under the given translation

"under a translation "<-1,2>under a translation <1,2>

(7,3)to(7-1,3+2)to(6,5)larrcolor(red)"new centre of B"(7,3)(71,3+2)(6,5)new centre of B

"to calculate d use the "color(blue)"distance formula"to calculate d use the distance formula

•color(white)(x)d=sqrt((x_2-x_1)^2+(y_2-y_1)^2)xd=(x2x1)2+(y2y1)2

"let "(x_1,y_1)=(2,7)" and "(x_2,y_2)=(6,5)let (x1,y1)=(2,7) and (x2,y2)=(6,5)

d=sqrt((6-2)^2+(5-7)^2)=sqrt(16+4)=sqrt20~~4.47d=(62)2+(57)2=16+4=204.47

"sum of radii "=5+4=9sum of radii =5+4=9

"since sum of radii">d" then circles overlap"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]}