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Trigonometry equalities, inequalities and expressions  sin, cos, tan, cot
by KarimTef » Wed Jul 20, 2016 6:05 pm
S. L. Looney in his book "Plane geometry", when he writes a formula, he notes next to it it's Article number. Example:
In page 11: cos (A + B) = cos A cos B  sin A sin B (Art. 88)
What are these articles? If they are gathered in a free downloadable document, I would like to have it.
Thank you.

KarimTef

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by Guest » Fri Jul 22, 2016 3:08 am
It simply refers to a later (or earlier) section of the same book. If you go to the section labelled 88 in the book he gives a proof of the formula.
Hope this helped,
R. Baber.

Guest

by KarimTef » Fri Jul 22, 2016 6:13 am
@Baber: Thank you very much.

KarimTef

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