C(UV) denotes the circle with diameter UV.
T(P,QR) denotes the tangential distance PS,
where point P lies outside C(QR), point S
lies on C(QR), and PS is tangent to C(QR).
Let A, B, C, and D be distinct, collinear
points in that order.
Construct a point E on line AD such that
EF = T(E,AB) = T(E,CD) = EG
(In reply to
Construction by brianjn)
Constructing this with Geometers Sketchpad results in EF = GE, but angles A'FE and C'GE are each larger than 90 degrees and so those two segments do not lie on a tangent line and the distances are therefore not the tangential distance.

Posted by Charlie
on 20101004 12:05:22 