Rotation about an arbitrary axis- X-Axis and Y-axis rotation

Discussion in 'Homework Help' started by zulfi100, Mar 27, 2015.

  1. zulfi100

    Thread Starter Member

    Jun 7, 2012
    320
    0
    Hi,
    I got a example related to 3d rotation about an abitrary axis. initially I have following diagram:
    3d rotation aaa1.png
    However after rotation about x-axis, the diagram changes to:
    3d roatation aaa2.png
    I cant understand how to draw the full cube? Why is there no downward perpendicular from A? Please guide me.

    Zulfi.
     
  2. MrAl

    Well-Known Member

    Jun 17, 2014
    2,439
    492
    Hi,

    What cube?
     
  3. zulfi100

    Thread Starter Member

    Jun 7, 2012
    320
    0
    Hi,
    Thanks for your reply. The first figure shows the cube but the second figure is not a cube. This is the thing which i want to understand. Please guide me.

    Zulfi.
     
  4. MrAl

    Well-Known Member

    Jun 17, 2014
    2,439
    492
    Hello again,

    Ok, if i understand you right, you are drawing a cube, then rotating it, then you want to draw it again.

    This isnt as hard as it may sound at first. There are 8 points that define the 8 corners of the cube. Rotate all 8, then connect the dots :)
    If you have trouble with determining what dots to connect, then draw more dots...start by rotating mid points between each corner and that will give you three dots per edge. If you want more, calculate more and perhaps plot them all, then view what you've plotted.
    A mid point can be found by using the mid point formula, then use two more times between that new point and the corners to get two more points, and if you do this enough times the cube will almost draw itself if you plot all the points.
     
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