A community for students.
Here's the question you clicked on:
 0 viewing
paulzord
 4 years ago
'complex' numbers?
Suppose w6 = 64i. Determine the six values of w.
paulzord
 4 years ago
'complex' numbers? Suppose w6 = 64i. Determine the six values of w.

This Question is Closed

paulzord
 4 years ago
Best ResponseYou've already chosen the best response.0hm i have no idea how to even start this...

mathgirl
 4 years ago
Best ResponseYou've already chosen the best response.0is this supposed to be w raised to the 6th power?

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2is this \[w^6=64i\]?

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2if so this is not so bad.

paulzord
 4 years ago
Best ResponseYou've already chosen the best response.0yes it is \[w ^{6} = 64i\]

mathgirl
 4 years ago
Best ResponseYou've already chosen the best response.0you just take the 6th root, right sat?

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2hello math girl. this site is very slow for me tonight

mathgirl
 4 years ago
Best ResponseYou've already chosen the best response.0figure out what number you multiply by itself 6 times

mathgirl
 4 years ago
Best ResponseYou've already chosen the best response.0that gives you 64, and then stick on i on it

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2yeah just take the 6th roots. if working in degrees write \[64i=64(\cos(270)+i\sin(270))\] and then take the 6ht root of 64 which is 2 and divide 270 by 6 to get 45 so first answer is \[2(\cos(45)+i\sin(45))\]

mathgirl
 4 years ago
Best ResponseYou've already chosen the best response.0where'd the trig stuff come from?

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2degrees means it is easier for me to divide and get whole number not write fractions in latex

mathgirl
 4 years ago
Best ResponseYou've already chosen the best response.0i must be confused about the type of problem here

paulzord
 4 years ago
Best ResponseYou've already chosen the best response.0how do yo know its 270?

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2think of where 64i is in the complex plane. it is straight down 64 units, so trig form is what i wrote. you can also use \[64i=64e^{\frac{3\pi}{2}i}\] and do it that way

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2oh how to i know it is 270?

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2draw the complex plane and imagine where 64i is. it is straight down 64 units, think of it as \[064i\]

mathgirl
 4 years ago
Best ResponseYou've already chosen the best response.0what math class is this? i never learned this stuff

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2you can do this as soon as you learn trig

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2write \[a+bi\] as \[r(\cos(\theta)+i\sin(\theta)\] where \[r=\sqrt{a^2+b^2}\] and \[\tan(\frac{b}{a})=\theta\]

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2in any case when you want the sixth roots, take the sixth root of the absolute value and divide the angle by 6

abtrehearn
 4 years ago
Best ResponseYou've already chosen the best response.1If\[w^{6} = 64 i,\]then\[w = \sqrt[6]{64}= 2.\]The angle \[\theta = 3 \pi/2,\]so one of the sixth roots of 64i will be a vertex of the regular hexagon lf side length 2 centered at z = 0, and making an angle \[\theta/6 = (3 \pi/2)/6 = \pi/4.\] That vertex is at\[z = 2 \cos(\pi/4) + 2i \sin(\pi/4) = \sqrt{2} + i \sqrt{2}.\]All the sixth roots are\[2 \cos(\pi/4 + k \pi/3) + 2i \sin(\pi/4 + k \pi / 3),\]where k is an integer.

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2so first answer is \[2(\cos(45)+i\sin(45)\] \[=2(\frac{\sqrt{2}}{2}+\frac{\sqrt{2}}{2}i)\] \[=\sqrt{2}+\sqrt{2}i\]

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2to get second answer just divide circle up into 6 equal parts with one part at 45 degrees. or go around the circle again and write \[64i=64(\cos(630)+i\sin(630))\] and now divide 630 by 6 to get 105 so second answer is \[2(\cos(105)+i\sin(105))\] etc

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2abtrehearn answer more elegant

paulzord
 4 years ago
Best ResponseYou've already chosen the best response.0how did you get that angle 3pi/2 when it looks like im meant to go tan 0/2

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2here is a picture of the unit circle in the complex plane. you can see that the angle associated with i is \[\frac{3\pi }{2}\]

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2and by the way it is \[\theta =\tan(\frac{b}{a})\] which is this case is \[\tan(\frac{64}{0})\] which is undefined

abtrehearn
 4 years ago
Best ResponseYou've already chosen the best response.1The angle\[3 \pi/2\]comes from plotting (0, 64) on the xy plane and measuring counterclockwise from the positive xaxis to the point. That's three right angles, or \[3 \pi/2\]radians.

paulzord
 4 years ago
Best ResponseYou've already chosen the best response.0no wonder the 6th root of it is pi/2?

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2if you want to do this the slow donkey way, which may not be a bad idea the first time you see it, start with 270 degrees (i know we really should work in radians but this will make my typing easier) then divide 270 by 6 for the next one add 360 to 270 to get 630, divide by 6 to get 105

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2then for the next one add 360 again to get 990 and divide by 6 to get 165 etc

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2around again you get 990+360=1350 divide by 6 to get 225 around again you get 1350+360=1710 divide by 6 get 285 around again you get 1710+360=2070 divide by 6 get 345 and finally around again you get 2070+360 = 2430 divide by 6 get 405 which is the same as 45 so you are back where you started

satellite73
 4 years ago
Best ResponseYou've already chosen the best response.2this is certainly not the elegant way to do it, but it gets the point across

abtrehearn
 4 years ago
Best ResponseYou've already chosen the best response.145 + 60 = 105 105 + 60 = 165 165 + 60 = 225 225 + 60 = 285 285 + 60 = 345. Those are the angles for the vertices in degrees.
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.