You are Here: Home >< Maths

# FP1 question

1. So I started doing FP1 and I'm confused..

Why isn't the argument of z, (pi + alpha) , in the first picture?

As for the 2nd pic, why isn't the argument of z, (2pi - alpha) ?
2. We normally use this thing called the principal argument, such that all arguments are within

Can you see why these values have been used now? You're technically correct in your thinking and the angles are accurate; it's just something of a convention.
3. The argument could be what you suggest or what is posted. The argument of z is simply the angle from the positive x axis. You could say an argument is pi/2, or you could say an argument is -3pi/2, because that would give you the same angle.

I have been taught to do it your way, and have a positive angle between 0 and 2pi. However, the approach shown is not incorrect.

It's pretty much just a matter of style or a convention. Like (sinx)^2 is normally written as sin^2 (x). Neither is wrong, and they both mean exactly the same thing, but one is simply more common.
4. (Original post by sabre2th1)
So I started doing FP1 and I'm confused..

Why isn't the argument of z, (pi + alpha) , in the first picture?

As for the 2nd pic, why isn't the argument of z, (2pi - alpha) ?

Take a look at page 15.
5. In exams they usually want you to give the principal argument, so get into the habit of producing this.
6. (Original post by Jam')
In exams they usually want you to give the principal argument, so get into the habit of producing this.
What board are you on? (or were you on?)
7. (Original post by Llewellyn)
What board are you on? (or were you on?)
OCR:MEI - bane of my life lol
8. (Original post by Jam')
OCR:MEI - bane of my life lol
But we have a Differential Equations module !
9. (Original post by Blazy)
But we have a Differential Equations module !
I wanted to do that. It looked interesting, but my school didn't teach it and I did FM in a year alongside A2 Maths, so I stuck to the familiar Mech and Stats modules - wasn't prepared to do heroics lol.

Have you just finished AS or A2?
10. (Original post by Jam')
We normally use this thing called the principal argument, such that all arguments are within

Can you see why these values have been used now? You're technically correct in your thinking and the angles are accurate; it's just something of a convention.

(Original post by Llewellyn)
The argument could be what you suggest or what is posted. The argument of z is simply the angle from the positive x axis. You could say an argument is pi/2, or you could say an argument is -3pi/2, because that would give you the same angle.

I have been taught to do it your way, and have a positive angle between 0 and 2pi. However, the approach shown is not incorrect.

It's pretty much just a matter of style or a convention. Like (sinx)^2 is normally written as sin^2 (x). Neither is wrong, and they both mean exactly the same thing, but one is simply more common.

(Original post by TDL)

Take a look at page 15.
Thanks, I understand

Write a reply… Reply
Submit reply

## Register

Thanks for posting! You just need to create an account in order to submit the post
1. this can't be left blank
that username has been taken, please choose another Forgotten your password?
2. this can't be left blank
this email is already registered. Forgotten your password?
3. this can't be left blank

6 characters or longer with both numbers and letters is safer

4. this can't be left empty
your full birthday is required
1. Oops, you need to agree to our Ts&Cs to register
2. Slide to join now Processing…

Updated: July 14, 2012
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Today on TSR

### Help!

Will Oxford nullify my offer?

Poll
Useful resources

## Make your revision easier

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

Can you help? Study help unanswered threads

## Groups associated with this forum:

View associated groups
Study resources

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

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