- #26

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For the second question, is it better to have ## \cos(60 + \alpha) ## or expand it? If you do, you'll have ## \cos ## or ## \sin ## separately. Think about that.Sorry, I can't find the other triangle of interest :( also what can I do with the first relation?

For the first question, you have used the three external equilateral triangles and the inner that you want to prove equilateral. There is exactly one triangle, that you have not used yet.

EDIT: Don't forget your goal. You must somehow end up with a relation that concludes about sides of the

*inner*triangle.

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