Nếu \(z = \cos \varphi - i\sin \varphi \) thì acgumen của z bằng:
(A) \(\varphi + k2\pi \left( {k \in Z} \right)\)
(B) \( - \varphi + k2\pi \left( {k \in Z} \right)\)
(C) \(\varphi + \pi + k2\pi \left( {k \in Z} \right)\)
(D) \(\varphi + \frac{\pi }{2} + k2\pi \left( {k \in Z} \right)\)
\(\begin{array}{l}
z = \cos \varphi - i\sin \varphi \\
= \cos \left( { - \varphi } \right) + i\sin \left( { - \varphi } \right)
\end{array}\)
có argumen bằng \( - \varphi + k2\pi \left( {k \in Z} \right)\)
Chọn (B).
-- Mod Toán 12
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