Assignment7
I construct two files about tangent
circle script tool.

You can use these script tools to make your own tangent circles
on. Clicking below.
Tangent
Circle 1
Tangent
Circle 2

My Discovery for Tangent Circle
While investigating for Tangent Circle
2, I found an interesting fact.
When I fix tangent points of both given
circles and move one given circle center (the point B in the picture
below), the tangent circle center (the point D) is on one line.
On the graph below, I trace the center
of the tangent circle with red color.
The line of the tangent circle center
goes throgh the center of one given circle that is fixed (the
point O above).
Even if I change the lenghs of radius,
the line of the tangent circle center does not change.
This means the slope of this line (ED/OE)
is constant.
The slope of this line depens only
on where the tangent point is.
You can check this fact by clicking
here, the GSP file I construct.
If you move point C, B(one of given
circle centers), or A (the radius of one given circle center),
the red line of the tangent circle center comes up.
Try making various slopes of tangent
circle center by changing the position of one of tangent points.

The discovery above was about the second
tangent circle.
Then, how about the first tangent circle?
I show a picture saying the similar
result, about the firlst one.
The tangent circle ceter in this case
is also on one line.

return