How do you multiply # (-2-5i)(-1-6i) # in trigonometric form?

1 Answer
Binayaka C.
May 2, 2016

In trigonometric form : #Z=32.46*(cos 148.74+ i sin 148.74)#

Explanation:

#(-2-5i)(-1-6i)= 2+17i+30i^2=2-30+17i= -28+17i# since # i^2=-1#
Modulas # r= sqrt ((-28)^2+17^2) =sqrt 1073 =32.46#
Argument #theta =180- tan^-1(17/28)= 148.74^0# As it lies on the 2nd quadrant the angle has been subtracted from #180^0# In trigonometric form : #Z=32.46*(cos 148.74+ i sin 148.74)#[Ans]

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