MathDB

We consider two circles

k_1(M_1, r_1)

and

k_2(M_2, r_2)

with

z = M_1M_2 > r_1+r_2

and a common outer tangent with the tangent points

P_1

and

P2

(that is, they lie on the same side of the connecting line

M_1M_2

). We now change the radii so that their sum is

r_1+r_2 = c

remains constant. What set of points does the midpoint of the tangent segment

P_1P_2

run through, when

r_1

varies from

0

c

Problem Statement