[TowerTalk] Elementary question - trig formula

[Pete Smith]

At the risk of getting into the dumb question territory:

If you know how far from the base of your tower your guys attach (on flat
ground), and you know how high they attach to the tower, then you should be
able readily to calculate how much turning radius inside the guys would
exist at any given height on the tower.  Obviously, this would be useful
for assessing a potential stack design.
						 I
						/I
                                        / I
                                       /  I C
                                      /   I
                                     /----I
                                    /  ?  I     
                                   /      I D
                                  /       I
                            -----/----B---I---------

That is, if you know the lengths of B and C+D, then you ought to be able to
figure out what "?" is for any length of C.  

Unfortunately, I've forgotten virtually all the plane geometry and trig
formulas I ever learned, and I didn't keep any high school math books.  I
think the two triangles involved are called "similar triangles," but that's
as far as my memory goes.  Can anyone tell me offhand what the right
formula is for this?  Once I have the fomula I can do the calculations, but
what to calculate? 

Thanks!




73,  Pete Smith N4ZR
In wild, wonderful, fairly rare WEST Virginia

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