How do you divide (3+4i) / (1+4i) 3+4i1+4i in trigonometric form?

1 Answer
Jul 28, 2017

The answer is =5/sqrt17(0.92-0.39i)=517(0.920.39i)

Explanation:

We start by writing numerator and denominator in polar form

z=z_1/z_2z=z1z2

The polar form of a complex number is

z=r(costheta+isintheta)....................(1)#

The numerator is

z_1=3+4i

r_1=|z_1|=sqrt((3)^2+(4)^2)=sqrt(9+16)=sqrt25=5

Therefore,

z_1=5(3/5+4/5i)

Comparing this equation to equation (1)

costheta=3/5 and sintheta=4/5

So,

we are in the quadrant I

theta=53.13^@

The polar form is

z_1=5(cos(53.13^@)+isin(53.13^@))=5e^(53.13i)

The denominator is

z_2=1+4i

r_2=|z_2|=sqrt((1)^2+(4)^2)=sqrt(1+16)=sqrt17

Therefore,

z_2=sqrt17(1/sqrt17+4/sqrt17i)

Comparing this equation to equation (1)

costheta=1/sqrt17 and sintheta=4/sqrt17

So,

we are in the quadrant I

theta=75.96^@

The polar form is

z_2=sqrt17(cos(75.96^@)+isin(75.96^@))=sqrt17e^(75.96i)

Terefore,

z=z_1/z_2=(5e^(53.13i))/(sqrt17e^(75.96i))

=(5/sqrt17)e^((53.13-75.96)i)

=(5/sqrt17)e^((-22.83^@)i)

=5/sqrt17(cos(-22.83^@)+isin(-22.83^@))

=5/sqrt17(0.92-0.39i)