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!

Homework Help: Polygon problem (? )

  1. Jan 19, 2010 #1
    polygon problem (?!!)

    Hi there!:smile:
    I have got an problem here.It's a simple one.Not much to think about
    "The ratio between the numbers of sides of two regular polygons is 1:2 and the ratio between the sum of their 3:4.Find the number of sides in each polygon"
    It appears easy and is too. but the problem is the answer i am getting is absolutely wierd ie.,
    -1 and -2 sides .:uhh:
    In the work out I had considered the no . of sides to be x and 2x
    the sum of interior angles 3y and 4y respectively.
    so it ends up as {(4x-4)*90} -{(2x-4)*90} =4y-3y
    so i sustituted it in the equation (2x-4)*90=3y which ends up as -4=4x .: x= -1:eek::uhh::
    Book's answers are polygon with 5 and 10 sides .
    I don't know whether I have gone wrong some where:confused:. If so Please help me correct it!(If the book's answer is wrong mention that too :smile:!)
    Thank you
  2. jcsd
  3. Jan 19, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper

    Hi 1/2"! :smile:
    If you mean "the ratio between the sum of their interior angles is 3:4", then I agree, the solution is -1 and -2 ! :biggrin:

    A solution of 5 and 10 would have a ratio of 3:8, not 3:4.
  4. Jan 23, 2010 #3
    Re: polygon problem (?!!)

    Thanks tiny-tim.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook