length of the shorter diagonal, given length of longer diagonal, lengths of sides of parallelogram
- Thread starter amemon
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Dr.Peterson
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What have you tried? What have you learned that might be helpful?
My first thought would be to use trigonometry to find the angles in the figure, and then use the results to find the other diagonal (solving a different triangle). But we can't help without seeing what help you need:
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By the way, this is not a differential equation; I'd expect it to be under Geometry and Trig.
Cubist
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Here's a possible starting point. Could you draw some extra lines on the following diagram which would facilitate finding the answer using Pythagoras' Theorem?
The Highlander
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Or, you could use the formulae given in the picture (below) to calculate cos A (or just 2xycosA) from the length of the longer diagonal and then the length of the shorter one once you know cos A (or 2xycosA).
Here is a parallelogram.
The length of the longer diagonal is 26 cm.
Work out the length of the shorter diagonal.
It would work equally well using the angle at B.
Whatever method you use, please come back and show us your working & answer (a picture will do) and, if any correction is needed, further advice will be offered or somone will confirm your work is correct.
Hope that helps.
