Ask Me Help Desk

Ask Me Help Desk (https://www.askmehelpdesk.com/forum.php)
-   Mathematics (https://www.askmehelpdesk.com/forumdisplay.php?f=199)
-   -   Octogon Volume (https://www.askmehelpdesk.com/showthread.php?t=257040)

  • Sep 5, 2008, 01:37 PM
    augustcab
    Octogon Volume
    Formula for calculating the voulume of an Octogon
  • Sep 5, 2008, 02:13 PM
    galactus
    An octagon has no volume. Though, It has area.

    You can derive a general formula.

    Let r equal the distance from the center to a vertex.

    We can break it up into 16 right triangles by drawing another line from the center to the middle of a side and then find the area of each.

    The angle of each triangle will be 22.5 degrees because 360/16=22.5.

    The area of a triangle is

    The area of each can be gotten from

    There are 16 such triangles, so we have

    So, the area of the octagon is

    If you need volume, multiply by the depth as well.

    Just enter your value of r and the depth, call it d, to find the volume.

    For that matter, you could Google octagon volume and find many things. I just came up with this one.
  • Sep 6, 2008, 10:30 AM
    Unknown008
    Galactus? You sure? An octagon has eight sides i think? So, 8, triangles instead of 16?

    Then, your final equation should be :



    EDIT: Oh, i didn't check the numbers... sorry, i need to check more carefully next time.
  • Sep 6, 2008, 10:44 AM
    galactus
    1 Attachment(s)
    I broke it up into 16 right triangles. Instead of the 8 isosceles. See what I mean?

    Since there are 16 of these little right triangles, we have

    If we use the 8 isosceles triangles each with area , we get

    Same thing. I should've done that before. Easier. A good check though.
  • Sep 6, 2008, 12:45 PM
    galactus
    That's OK Unknown. I doubt if the poster responds back anyway.

  • All times are GMT -7. The time now is 09:22 PM.