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How can I make an animation of line y=-3 that rotates by angle $\phi$ and the perpendicular distance from origin to this line. I also need to trace the shape that points of the intersection of the line with the perpendicular line makes.

Sorry, I forgot to mention that I also need a coordinate axes.

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1 Answer 1

up vote 10 down vote accepted

    \pnode(!\iA\space tan dup 0 eq { -3 0 }{1 exch div neg 5 mul 5} ifelse exch){C}
      \pnode(!\iC\space tan dup 0 eq { -3 0 }{1 exch div neg 5 mul 5} ifelse exch){Cb}%

Converted into a gif with:

convert -delay 50 -loop 0 -density 200 -scale 350 -alpha remove test.pdf test.gif

enter image description here

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I also need a coordinate axis. –  Student Mar 25 at 13:40
see edited answer –  Herbert Mar 25 at 13:52
This is line y=0, can you please change it to y=-3. and there is no perpendicular line from origin to the line in your solution. –  Student Mar 25 at 13:58
@Student: Which is the rotation point of the line? –  Herbert Mar 25 at 14:12
line y=-3, and the rotation point is (0,-3). Thanks. –  Student Mar 25 at 14:14

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