SOLUTION: -34/5-3i in polar form

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Question 1124676: -34/5-3i in polar form
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
The polar form of a complex number is another way to represent a complex number. The form z=a%2Bbi is called the rectangular coordinate form of a complex number.
The horizontal axis is the real axis and the vertical axis is the imaginary axis. We find the real and complex components in terms of r and theta where r is the length of the vector and theta is the angle made with the real axis.

From Pythagorean Theorem :
r%5E2=a%5E2%2Bb%5E2
By using the basic trigonometric ratios :
cos%28theta%29=a%2Fr and sin%28theta%29=b%2Fr
Multiplying each side by r
a=r%2Acos%28theta%29 and b=r%2Asin%28theta%29

The rectangular form of a complex number is given by:
z=a%2Bbi
Substitute the values of a and b
z=r%2Acos%28theta%29%2B%28r%2Asin%28theta%29%29i%26%238201%3B%26%238201%3B%26%238201%3B
z=r%28cos%28theta%29%2Bi%2Asin%28theta%29%29

you have:
+z=-34%2F5-3i
+z=+-6.8+-3i where a=-6.8 and b=-3

to write it in polar form, first find the absolute value of r

r=abs%28z%29=sqrt%28a%5E2%2Bb%5E2%29 if a=-6.8 and b=-3, we have
r=sqrt%28%28-6.8%29%5E2%2B%28-3%29%5E2%29
r=sqrt%2846.24%2B9%29
r=sqrt%2855.24%29
r+ » 7.43236
then
z=7.43236%28cos%28theta%29%2Bi%2Asin%28theta%29%29
Now find the argument theta
To find argument theta we will use one of the following formulas:
theta=arctan%28b%2Fa%29 if a%3E0
theta=arctan%28b%2Fa%29%2B180° if a%3C0


so you can use the formula theta=arctan%28b%2Fa%29%2B180° since you have a%3C0
theta=arctan%28-3%2F-6.8%29%2B180°
theta=arctan%283%2F6.8%29%2B180°
theta=24%B0%2B180°
theta=204°

polar form is:
z=7.43236%28cos%28204%29%2Bi%2Asin%28204%29%29