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Drawing a parallelogram (given a, the sum of the 2 diagonals and the angle between a and a diagonal)

  1. Oct 5, 2014 #1
    I'd really need help with this. Thanks.

    1. The problem statement, all variables and given/known data

    Draw a parallelogram:
    a = 4cm
    e + f (diagonals) = 11cm
    angle between a and e = 22°

    2. Relevant equations
    2 and 2 sides are parallel
    both diagonals halve each other
    (diagonal e goes from A to C)

    3. The attempt at a solution
    (attachment)
     

    Attached Files:

  2. jcsd
  3. Oct 5, 2014 #2

    ehild

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    Go ahead with your attempt! You have drawn the blue triangle. PRS is isosceles. Halve the side RS and draw a perpendicular at the halfpoint. It defines point P.

    ehild
    parallelogram.JPG
     
  4. Oct 5, 2014 #3
    Thanks, got it. You're a life saver. By the way: Why wouldn't this work if a = 8cm? Is it because a would be longer than the sum of e and b (if we take half of it as a triangle)? Or is there another explanation?
     
  5. Oct 5, 2014 #4

    ehild

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    a can not be longer than (e+f)/2. The yellow triangle would not exist.

    paral.JPG
     
  6. Oct 5, 2014 #5
    Thank you! (I menth something like that, yes)
     
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