Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    20
    ReputationRep:
    http://filestore.aqa.org.uk/subjects...W-MS-JUN15.PDF

    Question 5

    How does one accomplish part b?
    • Community Assistant
    • Welcome Squad
    Offline

    20
    ReputationRep:
    Community Assistant
    Welcome Squad
    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.
    Offline

    17
    ReputationRep:
    (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 \angle AOB is a right angle.
    • Community Assistant
    • Welcome Squad
    Offline

    20
    ReputationRep:
    Community Assistant
    Welcome Squad
    (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 \angle AOB 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
    Offline

    17
    ReputationRep:
    (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.
 
 
 
  • 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
    Would you like to hibernate through the winter months?
    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.