Look at the drawing below, where AB = BC = CD = DT = h, and TD perpendicular to AD:

                                   
                                   o T
                                   |
                                   | (h) 
                                   |
                                   |
  +----------+----------+----------o 
  A    (h)   B    (h)   C    (h)   D

The line AT makes an angle x with AD; the line BT makes an angle y with BD; the line CT makes an angle z with CD.

Using only geometry, prove that (angle x) + (angle y) = (angle z).

(In reply to Complex solution by goFish)

Where is point E?  It is where point T would be if it were on the complex plane, isn't it?

Are you an engineer?  Electrical engineers love complex numbers, other engineers to a lesser degree.  Mathematicians like them too, I suppose.

Good non-geometric solution.

Posted by MindRod on 2005-12-24 12:29:24