# Should you find theta?

Geometry Level 3

$\large x_n=2^n \cos n\theta$

For the given sequence we know that $$\large x_2=-\frac{28}{9}$$ and $$\large x_3=- \frac{184}{27}.$$

If $$x_4=\dfrac{A}{B},$$ where $$A$$ and $$B$$ are coprime positive integers, find $$A+B.$$

See Part 2.

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