Hey! Sign in to get help with your study questionsNew here? Join for free to post

Circles and gradients

Announcements Posted on
Take our survey to be in with the chance of winning a £50 Amazon voucher or one of 5 x £10 Amazon vouchers 28-05-2016
  1. Offline

    ReputationRep:
    http://www.thomas-reddington.com/upl...p_jan_2009.pdf

    For question 5a)

    In the mark scheme they are finding the gradeints for PQ and QR, then multiplying them, I have no idea why?
  2. Offline

    ReputationRep:
    Find the gradient of PQ, find the perpendicular for the gradient of QR, find the equation of QR, substitute the y value for a.

    You should be familiar with m1m2 = -1, another way of finding the perpendicular gradient.
  3. Offline

    ReputationRep:
    theyre perpandicular (because the triangle inside a semicircle is right angled) and hence the product of their gradients is -1.
    So from this it should be easy to work out your value for a
  4. Offline

    ReputationRep:
    (Original post by Joshmeid)
    Find the gradient of PQ, find the perpendicular for the gradient of QR, find the equation of QR, substitute the y value for a.

    You should be familiar with m1m2 = -1, another way of finding the perpendicular gradient.
    This is the first time i've seen of m1m2 = -1.
  5. Offline

    ReputationRep:
    (Original post by zoxe)
    This is the first time i've seen of m1m2 = -1.
    m1 is the gradient of PQ.

    Lets say PQ = 5 for example.

    we have m1m2 = -1

    We now substitute m1 = 5

    5m2 = -1

    m2 = -1/5
  6. Offline

    ReputationRep:
    ive solved it with Pythagoras, however i'm still baffled on how theyve done it
  7. Offline

    ReputationRep:
    (Original post by Joshmeid)
    m1 is the gradient of PQ.

    Lets say PQ = 5 for example.

    we have m1m2 = -1

    We now substitute m1 = 5

    5m2 = -1

    m2 = -1/5
    Why does PQ = gradient?

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: April 17, 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.

Today on TSR

Don't be a half-term hermit

How to revise this week and still have a life

Poll
What's your biggest deadly sin?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read here first

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