Finding a value

Are you familiar with DeMoivre's formula and the polar representation of complex numbers?

By the way, what have you thought about in this exercise, thus far?

Please see our FORUM GUIDELINES. :cool:
 
How can I find the value of cot (20) without using a calculator?

One way would be to use the following formula:

\(\displaystyle tan(3A) \ = \ \dfrac{3tan(A) \ - \ tan^3(A)}{1 \ - \ 3tan^2(A)}\)

and solve the resulting cubic equation....
 
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