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December 27th, 2017, 05:09 AM   #1
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Complex Number to Polar form with Real = 0!!!

Hello!

I have this complex number: $0 + j\times 89,75$

Our professor told us $0 + j\times 89,75$ to polar is: $89,75\angle 90$

He also told us Cartesian to polar convertion: $\sqrt{a^{2}+b^{2}}\angle{\tan^{-1}(b/a)}$

So let's convert $0 + j\times 89,75$ to polar:

First of all $\sqrt{a^{2}+b^{2}} = \sqrt{0^{2}+89,75^{2}} = 89,75$

but:
$\tan^{-1}(b/a)$ , a = 0!!!!! So how?

Last edited by skipjack; December 27th, 2017 at 10:22 AM.
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December 27th, 2017, 07:36 AM   #2
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Quote:
Originally Posted by babaliaris View Post
Hello!

I have this complex number: $0 + j\times 89,75$

Our professor told us $0 + j\times 89,75$ to polar is: $89,75\angle 90$

He also told as cartesian to polar conversation: $\sqrt{a^{2}+b^{2}}\angle{\tan^{-1}(b/a)}$

So let's convert $0 + j\times 89,75$ to polar:

First of all $\sqrt{a^{2}+b^{2}} = \sqrt{0^{2}+89,75^{2}} = 89,75$

but:
$\tan^{-1}(b/a)$ , a = 0!!!!! So how?
$\tan\left(\dfrac{\pi}{2} \right)$ is undefined, as is $\dfrac{b}{a}$ when $a=0$
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December 27th, 2017, 04:15 PM   #3
SDK
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You can't learn math if you still think its just a bunch of formulas. Put down the formula and just look at the vector you have written and tell me its polar angle. Once you do this, you will easily see how to correct the formula to account for this case.
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December 28th, 2017, 01:21 PM   #4
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Quote:
Originally Posted by SDK View Post
You can't learn math if you still think its just a bunch of formulas. Put down the formula and just look at the vector you have written and tell me its polar angle. Once you do this, you will easily see how to correct the formula to account for this case.


Sometimes you need to think before you ask something i guess
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