How do you write the complex number in trigonometric form #-5i#?

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Answer 1 · 2017-02-26T08:10:55

The answer is #=5(cos(-1/2pi)+isin (-1/2pi))#

The trigonometric form of a complex number is

#z=r(costheta+isin theta)#

Here, we have

#z=-5i#

Therefore,

#r=5#

#costheta=0#

#sin theta=-1#

So, #theta=-1/2pi#

#z=5(cos(-1/2pi)+isin (-1/2pi))#

#=5e^(-1/2ipi)#