[R] Draw a perpendicular line?

[CZ]

Thank you all for your suggestions and especially the codes.

Now I am able to solve it by finding the intercepts and slopes for both
lines first, and then I can find the coordinates of x and y at the
intersection.  At first I forgot how to use C to get the intercept of line
CD...  

Thanks again. 
-- 
View this message in context: http://r.789695.n4.nabble.com/Draw-a-perpendicular-line-tp2335882p2338864.html
Sent from the R help mailing list archive at Nabble.com.