1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Geometry problem

  1. Dec 21, 2011 #1
    1. The problem statement, all variables and given/known data
    Disparity is defined as [itex]\delta = \alpha - \beta[/itex]. Find [itex]\delta[/itex] in terms of interocular distance a, viewing distance D and d, e and f.

    http://img220.imageshack.us/img220/7576/43519392.jpg [Broken]

    3. The attempt at a solution

    I'm not getting anywhere. Any tips to get me started?
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Dec 21, 2011 #2
    I would start by writing down the tangent relations. For example, α is the difference between the two angles that Q and P make from the vertical (forward?) direction. So

    α = atan(f/(D+d)) - atan(e/D)

    and so forth.

  4. Dec 22, 2011 #3
    Thanks. Then:

    [itex]\beta = \arctan(\frac{a - e}{D}) - \arctan(\frac{a - f}{D + d})[/itex]

    Correct? Then I already have my answer it seems.
  5. Dec 22, 2011 #4
    Yes. It seems like you're about there. Don't forget the problem asks for δ=α-β.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Geometry problem
  1. A problem in geometry (Replies: 7)

  2. Geometry problem. (Replies: 1)

  3. Geometry of problem (Replies: 4)