Question #09598

1 Answer
May 18, 2016

There are three common tangents.

Explanation:

Generally speaking, equation
(x-a)^2+(y-b)^2=R^2(xa)2+(yb)2=R2
describes a circle of the radius RR with a center at point O(a,b)O(a,b).

The first equation can be transformed into
x^2+(y-1/2)^2=(1/2)^2x2+(y12)2=(12)2
This equation describes a circle of a radius 1/212 with a center at point (0,1/2)(0,12).

The second equation can be transformed into
x^2+(y+1/2)^2=(1/2)^2x2+(y+12)2=(12)2
This equation describes a circle of a radius 1/212 with a center at point (0,-1/2)(0,12).

Obviously, these two circles are tangential to each other with a common point at (0,0)(0,0).
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