Hey! Sign in to get help with your study questionsNew here? Join for free to post
 You are Here: Home >< Maths

# Argand diagram FP2

Announcements Posted on
Four hours left to win £100 of Amazon vouchers!! Don't miss out! Take our short survey to enter 24-10-2016
1. http://filestore.aqa.org.uk/subjects...W-MS-JUN15.PDF

Question 5

How does one accomplish part b?
2. You can construct a Cartesian equation for L because you know that the line perpendicular to it goes through the point 2-4i thus (2,-4) as well as the origin. You can work out the gradient of L by taking the negative reciprocal of the gradient from O to 2-4i. Once you have the equation, just see where the line intersects the axis and that should give you the points A and B. The mid point will be half of these co-ordinates along their respective axis (real and imaginary).

For the second part, it states the circle goes through A and B, therefore the centre is the mid-point between the two points. You know it goes though O so just take the magnitude of C for the radius of the circle.
3. (Original post by RDKGames)
For the second part, it states the circle goes through A and B, therefore the centre is the mid-point between the two points.
I don't think this is sufficient. You assume that A and B are diametrically opposite with no explanation. It must be mentioned that they are diametrically opposite since is a right angle.
4. (Original post by IrrationalRoot)
I don't think this is sufficient. You assume that A and B are diametrically opposite with no explanation. It must be mentioned that they are diametrically opposite since is a right angle.
It's 2 marks and they accept it without that explanation, but to be fair I was never really good at circle theorems to begin with so that's probably for the best
5. (Original post by RDKGames)
It's 2 marks and they accept it without that explanation, but to be fair I was never really good at circle theorems to begin with so that's probably for the best
Yeah you're right they don't require the explanation although they really should.

Dw I'm not great with circle theorems either (Still haven't tried proving them to this day! Really should soon.), recently I spent over an hour on a STEP Q unable to do it simply because I didn't remember a certain circle theorem lol.

Write a 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: June 23, 2016
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

### Who is getting a uni offer this half term?

Find out which unis are hot off the mark here

Poll
Useful resources

## Make your revision easier

### Maths Forum posting guidelines

Not sure where to post? Read here first

### 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.