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Question: Rotation angle of an ellipse

Question:Rotation angle of an ellipse

tsunamiBTP 292 Maple
October 31 2010
0

I am attempting to define the rotation angle of an ellipse about the cartesian coord frame @ (0,0).  I am pretty sure the slope of the tangency vector @ both the major & semi-major axis is orthogonal to the vector originating from the origin from (0,0) with a length of a or b depending on which axis I am using.

My thought was in the case of the major axis that x = a*cos(theta) & the slope of the vector emanating from the origin is tan(theta).  So if I set dy/dx = -1/tan(theta & substitute x = acos(theta) I can resolve theta?

My results do not seem to be working.  Anyone have any insight?  I will try to upload my image of my derivation.
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