# Can someone help me out with a math/geometry issue?

Discussion in 'The Okie Corral' started by harlenm, Feb 18, 2010.

1. ### harlenmMillennium Member

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See the diagram. Hopefully it is understandable.

2. ### eingeist

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Remember that triangles always add up to 180 degrees.

Use a^2 + b^2 = c^2 to find your measurements. Take 90 degrees (the right angle at E), and solve with pythagorean theorem.

You can use Sine and Cosine to find angle by using the arcsine or arccosine, or you can use dot product with vectors..

This for a class or are you just looking for an answer?

3. ### harlenmMillennium Member

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Not a class. I replaced the projectors in my headlights, and the passenger side points too far to the right. So, I parked in front of my garage, measured the distance to it, which was 13.5 feet. My lights are exactly 5 feet from center to center, and the center of the beams on the garage were exactly 6 feet apart. Just trying to get an angle to tell the installer, hey it's pointing 5 degrees to the right.(or whatever it is)

4. ### eingeist

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It is almost 5 degrees.

Inverse Tangent of 13.5/1 is 85.7. Add that to 90, and the difference between that and 180 is 4.24 degrees.

5. ### eingeist

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Angle E is 90 deg, angle D is 85.7, and angle C is 4.24

BTW, BE is 5 feet. You want BD to be 5 feet.

Hope this helps...

6. ### harlenmMillennium Member

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Thanks. Guess that was a pretty good guess on my part!

7. ### eingeist

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No prob. Just wing it... lol.

I'm sure they can't adjust those things THAT accurately anyway. It's probably a little bit of trial and error. But that'll get you pretty close if they can come close to that angle.

8. ### Playin104Packin' Heat

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You're looking at it the wrong way....here it is simplified:
I don't have a calculator or I would do the math.

9. ### Playin104Packin' Heat

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never mind.....he beat me to it.

10. ### eingeist

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I think at 13.5 feet from his garage door, his right headlamp is pointing a foot to the right... At least that's the way I see it..

Your diagram shows it being 5 feet to the right.

If that is the case, I'll redo the math.. But I think I read it right..

edit: it's time for me to get to bed, but harlenm, if your right headlamp is 5 feet to the right of where it should be, use 20.3 degrees.
If it's one foot off, use 4.24 or close.

Last edited: Feb 18, 2010
11. ### harlenmMillennium Member

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Of course it's not an exact science, but atleast I can give him an idea of how much to try and turn it.

12. ### Playin104Packin' Heat

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Oooops...that is suppose to be 1 not 5

13. ### harlenmMillennium Member

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This is correct.

14. ### Playin104Packin' Heat

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Yeah, the math is right....my diagram is wrong, typo....

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