polar formof the complex number-2-1
Answers
Step-by-step explanation:
The polar form of a complex number is another way to represent a complex number. The form z=a+bi 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 θ where r is the length of the vector and θ is the angle made with the real axis.
From Pythagorean Theorem :
r2=a2+b2
By using the basic trigonometric ratios :
cosθ=ar and sinθ=br .
Multiplying each side by r :
rcosθ=a and rsinθ=b
The rectangular form of a complex number is given by
z=a+bi .
Substitute the values of a and b .
z=a+bi =rcosθ+(rsinθ)i =r(cosθ+isinθ)
In the case of a complex number, r represents the absolute value or modulus and the angle θ is called the argument of the complex number.
This can be summarized as follows:
The polar form of a complex number z=a+bi is z=r(cosθ+isinθ) , where r=|z|=a2+b2−−−−−−√ , a=rcosθ and b=rsinθ , and θ=tan−1(ba) for a>0 and θ=tan−1(ba)+π or θ=tan−1(ba)+180° for a<0 .
Example:
Express the complex number in polar form.
5+2i
The polar form of a complex number z=a+bi is z=r(cosθ+isinθ) .
So, first find the absolute value of r .
r=|z|=a2+b2−−−−−−√ =52+22−−−−−−√ =25+4−−−−−√ =29−−√ ≈5.39
Now find the argument θ .
Since a>0 , use the formula θ=tan−1(ba) .
θ=tan−1(25) ≈0.38
Note that here θ is measured in radians.
Therefore, the polar form of 5+2i is about 5.39(cos(0.38)+isin(0.38)) .