Results 1 to 5 of 5

Thread: octagon

  1. #1
    Member
    Joined
    Sep 2009
    Posts
    83

    octagon

    Hello everyone, I do not know if I am solving this problem well,

    perhaps not so simple as I see it:

    Two octagons equal have a common side. Find the angle between the sides of both polygons consecutive common.Find the area of the figure if the side is 2m.


    I draw on the figure I made:



    And according to the following theory:

    In a regular octagon, with sides and angles that are equal, the sides are joined at an angle of 135 degrees or \displaystyle\frac{3\pi}{4} rad. Each outer corner of the regular octagon is 45 º or \displaystyle\frac{\pi}{4}  rad.

    And so I think then that the sum 45 + 45 = 90 degrees to the exterior angle formed by the two side keys names to common.


    Furthermore, the area of an octagon side t is:

    A = 2t^2(1 + \sqrt[ ]{2})

    I am well on these considerations?

    A greeting and thank you very much
    Attached Thumbnails Attached Thumbnails octagon-octagon.jpg  
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,275
    Thanks
    390
    Hello, Dogod11!

    You're right on both counts!

    That exterior angle is 90°.

    And your area formula is correct.

    Good work!

    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    May 2009
    Posts
    41
    Quote Originally Posted by Dogod11 View Post
    Hello everyone, I do not know if I am solving this problem well,

    perhaps not so simple as I see it:

    Two octagons equal have a common side. Find the angle between the sides of both polygons consecutive common.Find the area of the figure if the side is 2m.


    I draw on the figure I made:



    And according to the following theory:

    In a regular octagon, with sides and angles that are equal, the sides are joined at an angle of 135 degrees or \displaystyle\frac{3\pi}{4} rad. Each outer corner of the regular octagon is 45 º or \displaystyle\frac{\pi}{4}  rad.

    And so I think then that the sum 45 + 45 = 90 degrees to the exterior angle formed by the two side keys names to common.


    Furthermore, the area of an octagon side t is:

    A = 2t^2(1 + \sqrt[ ]{2})

    I am well on these considerations?

    A greeting and thank you very much




    Is correct!!The area if the octagon have to be right!
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member
    Joined
    Sep 2009
    Posts
    83
    Thanks!!
    Follow Math Help Forum on Facebook and Google+

  5. #5
    EX5
    EX5 is offline
    Newbie
    Joined
    Jan 2010
    Posts
    1

    Nice

    I found no fault in your calculations, good job.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Thorn Octagon
    Posted in the Math Topics Forum
    Replies: 1
    Last Post: June 1st 2011, 06:47 AM
  2. Right angles in Octagon
    Posted in the Geometry Forum
    Replies: 1
    Last Post: April 17th 2010, 10:14 PM
  3. Octagon!
    Posted in the Geometry Forum
    Replies: 1
    Last Post: January 18th 2010, 10:24 PM
  4. Area of Octagon
    Posted in the Geometry Forum
    Replies: 8
    Last Post: September 10th 2008, 04:25 PM
  5. Help! Octagon
    Posted in the Geometry Forum
    Replies: 4
    Last Post: September 25th 2006, 06:20 AM

Search Tags


/mathhelpforum @mathhelpforum