Slope 0-90 lines between two points [closed]

Slope 0-90 lines between two points [closed]

References

Reference NO 1

http://stackoverflow.com/questions/11667744/slope-of-line-between-two-points-with-same-x

Reference NO 2

http://civil.engr.siu.edu/surveying/classes/263.ppt

Reference NO 3

http://satheshkumar.puzl.com/puzl/files/727/26273/510e287d13a17.pdf

Reference NO 4

http://www.haesemathematics.com.au/samples/sa12mm-2_03.pdf

Reference NO 5

http://www.ima.umn.edu/~trenev/old_files/m131/Chapter1.pdf

Reference NO 6

http://www.tug.org/TUGboat/tb10-2/tb24salomon.pdf

Reference NO 7

#EANF#

Reference NO 8

#EANF#