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12. Rectangular to Polar form of complex number example ( Enter your problem )

1. Example-1





1. `A=5+6i`
Find Polar form of complex number


Solution:
Here `A=5+6i`

For a complex number `z=a+bi`, the polar form is `z=r*(cos(theta)+i*sin(theta))`

where `r=sqrt(a^2+b^2)` and `theta=atan(b/a)`


Here, `a=5` and `b=6`

`:. r=sqrt(5^2+6^2)=sqrt(25+36)=sqrt(61)=7.8102`

`theta=atan(b/a)` (Since `a>0`)

`:. theta=atan((6)/(5))`

`:. theta=atan(1.2)`

`:. theta=50.1944 ^circ` or `theta=0.8761` rad

`:.` The polar form (in degree) is `7.8102*(cos(50.1944)+i*sin(50.1944))`

`:.` The polar form (in radian) is `7.8102*(cos(0.8761)+i*sin(0.8761))`
2. `A=-2+3i`
Find Polar form of complex number


Solution:
Here `A=-2+3i`

For a complex number `z=a+bi`, the polar form is `z=r*(cos(theta)+i*sin(theta))`

where `r=sqrt(a^2+b^2)` and `theta=atan(b/a)`


Here, `a=-2` and `b=3`

`:. r=sqrt((-2)^2+3^2)=sqrt(4+9)=sqrt(13)=3.6056`

`theta=atan(b/a)+180` (Since `a<0`)

`:. theta=atan((3)/(-2))+180`

`:. theta=atan(-1.5)+180`

`:. theta=-56.3099+180`

`:. theta=123.6901 ^circ` or `theta=2.1588` rad

`:.` The polar form (in degree) is `3.6056*(cos(123.6901)+i*sin(123.6901))`

`:.` The polar form (in radian) is `3.6056*(cos(2.1588)+i*sin(2.1588))`
3. `A=1-3i`
Find Polar form of complex number


Solution:
Here `A=1-3i`

For a complex number `z=a+bi`, the polar form is `z=r*(cos(theta)+i*sin(theta))`

where `r=sqrt(a^2+b^2)` and `theta=atan(b/a)`


Here, `a=1` and `b=-3`

`:. r=sqrt(1^2+(-3)^2)=sqrt(1+9)=sqrt(10)=3.1623`

`theta=atan(b/a)` (Since `a>0`)

`:. theta=atan((-3)/(1))`

`:. theta=atan(-3)`

`:. theta=-71.5651 ^circ` or `theta=-1.249` rad

`:.` The polar form (in degree) is `3.1623*(cos(-71.5651)+i*sin(-71.5651))`

`:.` The polar form (in radian) is `3.1623*(cos(-1.249)+i*sin(-1.249))`




This material is intended as a summary. Use your textbook for detail explanation.
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