Is it possible to calculate the angles within a parallelogram knowing only the diagonals? The lengths of the diagonals may change, but the perimeter will remain constant.

Essentially I want to be able to work out how far from a rectangle the parallelogram is in terms of degrees.

  • $\begingroup$ It is now hard to understand what the problem is - do you, for example, know the perimeter and the length of one diagonal? Or are you looking to analyse a slightly flexed rectangle? $\endgroup$ – Mark Bennet Mar 20 '14 at 15:21
  • $\begingroup$ @MarkBennet; We are working the a rolled slab of steel. The goal is a perfect rectangle, but this can be difficult. If I know only the length of the diagolals, is it possible to convert this to an angle? I can solve it by taking additional measurements of the piece, but would like to do it without if possible. Doees this make sense? $\endgroup$ – xgstr Mar 24 '14 at 8:42

Imagine two pieces of wood (of different lengths) joined at the middle so they can rotate relative to each other. As they rotate they form the diagonals of different parallelograms with different angles. [If they are the same length you only get rectangles]

  • $\begingroup$ Thanks for your response, I have refined the question as it was not clear. $\endgroup$ – xgstr Mar 20 '14 at 15:18

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