Turn on thread page Beta
    • Thread Starter
    Offline

    2
    ReputationRep:
    Hi

    I'm stuck on this question (please see attachment) and I just can't seem to work it out! I had this wild idea of working out the angle at the top of the sector in the segment and going from there, but that didn't work! I can't link together the two pieces of info they give, the length of Ab and the height from Ab to P. Please help!
    Attached Images
     
    Offline

    2
    ReputationRep:
    You see where the angle theta is marked, the right angle triangle formed there, until the side hits the line AB is R-10.
    Offline

    2
    ReputationRep:
    So Using Phythagoras : r2 = (r-10)^2 + 50^2 20r = 260 r = 130
    Offline

    2
    ReputationRep:
    To find the length of the sector:
    Find the angle: sinx = 50/130 x = 0.395 radians
    l=130 x X = = 51.3

    Im not too sure about this so can someone tell me if its right?
    Offline

    0
    ReputationRep:
    a)'s easy. u can work out b) on your own.

    Not sure if the image is attached correctly
    Attached Images
     
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by LondonBoy)
    To find the length of the sector:
    Find the angle: sinx = 50/130 x = 0.395 radians
    l=130 x X = = 51.3

    Im not too sure about this so can someone tell me if its right?
    I used cosine rule for part b:
    cos A = 130² + 120² - 50²/ 2(130)(120)
    = 0.92309...
    A = 0.39479..
    θ = 0.39479 x 2 = 0.78958..

    so l= 130 X 0.78958
    = 102.6454
    = 103 cm

    Thanks for your help guys.
 
 
 
The home of Results and Clearing

3,090

people online now

1,567,000

students helped last year

University open days

  1. Bournemouth University
    Clearing Open Day Undergraduate
    Wed, 22 Aug '18
  2. University of Buckingham
    Postgraduate Open Evening Postgraduate
    Thu, 23 Aug '18
  3. University of Glasgow
    All Subjects Undergraduate
    Tue, 28 Aug '18
Poll
How are you feeling about GCSE results day?
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

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

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