What is the trigonometric form of (-2-9i) ?

1 Answer
Topscooter
Dec 18, 2015

sqrt(85)e^(iarccos(-2/85))

Explanation:

You first need the module of this complex number, given by the formula abs(-2-9i) = sqrt((-9)^2 + (-2)^2) = sqrt85.

You can now factorize the complex number by its module : -2-9i = sqrt(85)(-2/85 -i9/85). You can now say that EEtheta in RR such that cos(theta) = -2/85 and sin(theta) = -9/85.

So theta = arccos(-2/85).

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