Turn on thread page Beta

Maths C2: Seems extremely simple but I don't get it!! watch

    • Thread Starter
    Offline

    0
    ReputationRep:
    Currently Updating Question
    Offline

    13
    ReputationRep:
    (Original post by TwentyTen)
    I know the principles, but I don't understand the proofs


    The angle at the centre of a circle is twice the angle at the circumference.

    Proof:

    Let angle ACO=a and angle AOX=y

    Angle CAO = angle ACO (isosceles triangle)

    Therefore angle CAO = a


    I get that bit, this is the bit that's confusing....

    Hence y= 2a (exterior angle of triangle AOC)


    Why?...How?
    if AOX is the angle at the center, then it has to be 2x the angles at the circumference therefore if Y is the angle at the center and a stands for one of the angels at the circumference then 1/2y=a or y=2a
    because the angels have equal angels they can be expressed as a but because the angle at the center is double you make it 2a=y
 
 
 
Poll
How are you feeling in the run-up to Results Day 2018?
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.