Hey there! Sign in to join this conversationNew here? Join for free

Complex numbers. Watch

Announcements
    • Thread Starter
    Offline

    3
    ReputationRep:
    Thanks.
    Offline

    1
    ReputationRep:
    Square your answers, do you get -15 - 8i? but it's not normal to write your angle out in terms of a decimal (which you have most likely cut off the rest of the expansion). If your using Pi, leave it in terms of Pi - much easier to deal with later on.

    I would expect it to be much easier to say if a + bi was a square root of -15 - 8i, then (a + bi)^2 = -15 - 8i ....
    • Thread Starter
    Offline

    3
    ReputationRep:
    .........
    Offline

    0
    ReputationRep:
    Your value for theta is wrong - 28 degrees would mean the point was somewhere in the first quadrant. As well as finding arctan(y/x), you need to consider whether you should add/subtract pi radians to the argument (since arctan(-y/-x)=arctan(y/x)).
    • Thread Starter
    Offline

    3
    ReputationRep:
    (Original post by Mark13)
    Your value for theta is wrong - 28 degrees would mean the point was somewhere in the first quadrant. As well as finding arctan(y/x), you need to consider whether you should add/subtract pi radians to the argument (since arctan(-y/-x)=arctan(y/x)).
    Bingo.....that's where I was going wrong, I needed to do 360 - theta......thanks a lot, much appreciated
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Will you be richer or poorer than your parents?
    Useful resources

    Make your revision easier

    Maths

    Maths Forum posting guidelines

    Not sure where to post? Read the updated guidelines here

    Equations

    How to use LaTex

    Writing equations the easy way

    Student revising

    Study habits of A* students

    Top tips from students who have already aced their exams

    Study Planner

    Create your own Study Planner

    Never miss a deadline again

    Polling station sign

    Thinking about a maths degree?

    Chat with other maths applicants

    Can you help? Study help unanswered threads

    Groups associated with this forum:

    View associated groups
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.