Concurs "Teodor Topan" - problema 1

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maky
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Concurs "Teodor Topan" - problema 1

Post by maky »

Sa se arate ca daca \( z=cos\alpha+isin\alpha \) atunci:
a)\( cosn\alpha=\frac{z^{2n}+1}{2z^n} \), \( sinn\alpha=\frac{z^{2n}-1}{2iz^n} \)
b) Calculati produsul \( P={cos20^o}\cdot{cos40^o}\cdot{cos80^o} \)
Gurzau Ileana, Cehu Silvaniei
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