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-   -   Angles of pentagons (https://www.askmehelpdesk.com/showthread.php?t=302765)

  • Jan 12, 2009, 07:11 PM
    mellib429
    Angles of pentagons
    I have another quesiton.
    This worksheet my teacher gave me says that a pentagonal beasball diamond has three right angles and the other two are congruent.
    Well I know that the angle measures of a pentagon add up to 520
    And that 3 90 degree angles equal 270.
    Well when subtracting 270 from 520
    I got 250 and then I divided that in half and got 125.
    But that wasn't one of the answers.
    Is this right or did I do something wrong?
    The only answer close to the answer I got was 135.
    The others were 54 67.5 and 90
  • Jan 12, 2009, 07:14 PM
    mellib429
    Never mind.
    The angle measures of a pentagon equal 540.
  • Jan 14, 2009, 06:42 PM
    Credendovidis
    Quote:

    Originally Posted by mellib429 View Post
    The angle measures of a pentagon equal 540.

    Good : a little thinking often solves the problem !
    You'll never forget that 540 degrees now !

    Remember :

    Internal angles of a regular :

    3 - Triangle = 60 deg - total = 180 deg
    4 - Square = 90 deg - total = 360 deg
    5 - Pentagon = 108 deg - total = 540 deg
    6 - Hexagon = 120 deg - total = 720 deg
    7 - (H)Septagon = 128.57 deg - total = 900 deg
    8 - Octagon = 135 deg - total = 1080 deg
    9 - Nonagon = 140 deg - total = 1260 deg
    10-Decagon = 144 deg - total = 1440 deg

    :)


    .

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