# [pstricks] Right angle symbol in a 2D Projection

Michael Sharpe msharpe at ucsd.edu
Sun Feb 8 01:05:31 CET 2009

On Feb 7, 2009, at 3:17 PM, Juergen Gilg wrote:

> \psellipticarc{->}(0,1.4)(0.2,0.11){120}{420}

Perhaps it would be easier not to use \psellipticarc, for in general
that will require further rotation. If you have a right angle AOB in
three dimensions and a circular arc with center O, its projection on a
two dimensional plane may thought of as the vector parametric curve AA
cos t+BB sin t, 0\le t\le \pi/2, where AA and BB are the projections
on the plane of points on OA, OB at equal distance from the origin.
This should look better, as the tangents at the endpoints will have
the correct directions.

Michael