[R] Draw a perpendicular line?
cxzhang at ualr.edu
Tue Aug 24 00:04:41 CEST 2010
I am trying to draw a perpendicular line from a point to two points.
Mathematically I know how to do it, but to program it, I encounter some
problem and hope can get help. Thanks.
I have points, A, B and C. I calculate the slope and intercept for line
drawn between A and B.
I am trying to check whether I can draw a perpendicular line from C to line
AB and get the x,y value for the point D at the intersection.
Assume I get the slope of the perpendicular line, I will have my point (D)
using variable x and y which is potentially on line AB. My idea was using
|AC|*|AC| = |AD|*|AD|+ |CD|*|CD|. I don't know what function I may need to
call to calculate the values for point D (uniroot?).
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