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$$A=\left(\begin{array}{cc}\mathrm{sen}\frac{\pi }{2}& \cos \frac{\pi }{2}\\ \mathrm{tg}\pi & \mathrm{sen}\frac{2\pi }{5}\end{array}\right)$$ e $$B=\left(\begin{array}{cc}\sec \frac{2\pi }{5}& \cos \frac{2\pi }{5}\\ \cos \pi & \mathrm{cotg}\frac{\pi }{2}\end{array}\right)$$ Se $a=\det A$ e $b=\det B$, então o número complexo $a+bi$ tem módulo igual a: