#### Berthin Alexander

##### New member

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- Thread starter Berthin Alexander
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- Jun 16, 2020

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- Joined
- Jun 16, 2020

- Messages
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I got 0=0The interior angles of a quadrilateral have a sum of 360 degrees. So if you can find an expression for <EDC, you can form an equation. Does that help?

- Joined
- Jun 16, 2020

- Messages
- 14

thank you very much for uploading your solution. it's very interesting and coolThere doesn't seem to have been any progress, so at least here is a trigonometric method for anyone interested. I'm sure there's a much nicer geometric method!

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