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## Venomblast 3 years ago put this in polar form 5-12i

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1. Venomblast

i got r=13

2. Venomblast

I do not want my answers in degree

3. Venomblast

basically what i need help is converting my answer to degree to rad in decimal

4. terenzreignz

So you already have your angle in degrees?

5. Venomblast

292.61 degree.

6. terenzreignz

In that case, if you have it in degrees, to bring it to radians, simply multiply it by the factor $\huge \frac{\pi}{180^o}$

7. Venomblast

|dw:1367393591344:dw|

8. agent0smith

|dw:1367393361730:dw| for a number a+bi $\large r^2 = a^2 + b^2$ tan theta = $\large \tan \theta = \frac{ b }{a }$ To convert from degrees to radians $\Large \theta ^{r} = \theta ^{d} \times \frac{ \pi }{180}$ theta d means theta in degrees.

9. Venomblast

hey one more question. if 5 was negative would it still be $\tan \theta b/a$ or will the a be negative?

10. agent0smith

Like this? |dw:1367393943561:dw| $\tan \theta = \frac{ -12 }{-5 }$ which gives theta = 67.4 degrees or 1.18 radians... BUT as you can see, theta is in the third quadrant, so you need to add 180 degrees to 67.4 degrees, or add pi radians to 1.18 radians... giving 247.4 degrees or 4.31 radians. This is why drawing a diagram is helpful.

11. Venomblast

no what I am trying to say is, does it matter of a or b is positive or negative or do you just take the absolute value of 12 and 5 when figuring out tan theta

12. agent0smith

Oh, no, you use b and a exactly as they are, you can take the abs value, but that just means more work to find the actual angle.

13. agent0smith

Because tan is negative in the 2nd and fourth quadrants, so it's helpful to keep the negatives as they are: http://upload.wikimedia.org/wikipedia/commons/thumb/a/a7/All_Students_Take_Calculus.svg/220px-All_Students_Take_Calculus.svg.png

14. Venomblast

i tan is always positive if you take the abs of a and b

15. agent0smith

Eh? we don't want tan to always be positive... there's no need for that. Keeping the negatives can actually save you some work...

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