Welcome, Guest. Please login or register. Did you miss your activation email?

Author Topic: Math: Finding a point that is perpendicular to another point.  (Read 2055 times)

0 Members and 1 Guest are viewing this topic.

aaranaf

  • Newbie
  • *
  • Posts: 4
    • View Profile
Math: Finding a point that is perpendicular to another point.
« on: August 03, 2013, 01:23:52 am »
So here's what I want to do. I want to find the point in 2d-space for C.
I have the point A and B and the distance from B to C.
I know C is perpendicular to B. If someone could point me in the right direction on this it would be greatly appreciated.

The Hatchet

  • Full Member
  • ***
  • Posts: 135
    • View Profile
    • Email
Re: Math: Finding a point that is perpendicular to another point.
« Reply #1 on: August 03, 2013, 02:08:38 am »
Go to google and put in "find point perpendicular to line"

rgrant1993

  • Newbie
  • *
  • Posts: 12
    • View Profile
Re: Math: Finding a point that is perpendicular to another point.
« Reply #2 on: August 03, 2013, 08:25:55 pm »
We need to know the data you have recorded inorder to know the data we need to find.

Grimshaw

  • Hero Member
  • *****
  • Posts: 631
  • Nephilim SDK
    • View Profile
Re: Math: Finding a point that is perpendicular to another point.
« Reply #3 on: August 03, 2013, 08:37:41 pm »
(direction from A to B)
V = B - A
V' = normalize(V)

(vector orthogonal to V' - perpendicular)
O = (-V'y, V'x)

(finally find point C by going from B in the orthogonal direction)
C = B + O * distance

I am a little fuzzy right now but if something is wrong here ill get back to you

gostron

  • Jr. Member
  • **
  • Posts: 53
    • View Profile
Re: Math: Finding a point that is perpendicular to another point.
« Reply #4 on: August 05, 2013, 01:02:44 pm »
May I add that knowing the distance and that it's perpendicular gives your two points, one for each side.

for a vector defined by (a,b) an orthogonal vector would be (-b, a) (so I do agree with Grimshaw, just to say it a bit differently)