How do you find #abs( -3 i )#?

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Answer 1 · 2016-10-27T01:42:57

#abs(-3i) =3#

The absolute value of a number is its distance from the origin,
So if we take our complex number with cartesian coordinates,

#(0,-3)# or #0-3i#

to work out its distance we use Pythagoras's theorem.

#c^2=a^2+b^2#

with #c=abs(("a , b)")#

so to find out c,

#c=sqrt(a^2+b^2)#

#c=sqrt((0)^2+(-3)^2)#

#c=sqrt(9)#

#c=3#

#abs(-3i) =3#