Can someone check my Trig (Trig Form and Demoive's Theorm

[killasnake]

Hi can someone check this to see if it's correct.

Trig Form

(4-3i) into Trig form

r= Sqrt (4^2+(-3)^2
r= Sqrt (25)
r= 5

tan = -(3/4) = -.01309
arctan = -.74995
2pi -.74995
= 5.5332

Z= 5 (cos 5.5332 + i sin 5.5332)
---------------------------
I got confused with the Demoive question

r= Sqrt (11^2+1)
r= Sqrt (122)

tan 1/11 = .001586 <----- Is this right?
arctan (.001586) = .09087103
2pi + .09087103
= 6.19231

Put it into Trig form
Z= Sqrt(122) (cos 6.19231 + i sin 6.19231)

Demoiver's

z^6 = Sqrt (122)^6 (cos 6.19231 + i sin 6.19231) ......

First I don't even know if that is right. Also, if it is right I do not know the next step to completing the problem.

Thanks

 

[tkhunny]

1) You must make up your mind if your calculator is in degrees or radians. You've quite a hodgepodge going on in there.

2) Remember your Quadrant. It will save you from yourself.

3) You didn't tell us the trig form of the second one. 11 + i, maybe? This is in Quadrant I. Guess where 6.19231 is? Whoops.

 

[killasnake]

Opps The question for the DeMoivers

Its (11+i)^6