# Writing a number in trigonometric form

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• Nov 3rd 2009, 04:59 PM
Sugar Sana
Writing a number in trigonometric form
I feel dumb asking this, but I cant get the right answer...

Write in Trigonometric form

9.6-5.5i
• Nov 3rd 2009, 05:59 PM
pickslides
I think you require

given $z = a+bi$

then

$z = \sqrt{a^2+b^2}~\text{cis}\left(\tan^{-1}\left(\frac{b}{a}\right)\right)$