Lösung 3.2:6d

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Version vom 10:41, 11. Mär. 2009

We can determine the number's magnitude directly using the distance formula,

\displaystyle \begin{align}

\bigl|\sqrt{10}+\sqrt{30}i\bigr| &= \sqrt{\bigl(\sqrt{10}\,\bigr)^2+\bigl(\sqrt{30}\,\bigr)^2}\\[5pt] &= \sqrt{10+30}\\[5pt] &= \sqrt{40}\\[5pt] &= \sqrt{4\cdot 10}\\[5pt] &= 2\sqrt{10}\,\textrm{.} \end{align}

In addition, the number lies in the first quadrant and we can therefore determine the argument using simple trigonometry.

Image:3_2_6_d_bild.gif Image:3_2_6_d_bildtext.gif

The polar form is

\displaystyle 2\sqrt{10}\Bigl( \cos\frac{\pi}{3} + i\sin\frac{\pi}{3} \Bigr)\,\textrm{.}