Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    Hi,

    I have a question on my FSMW Additional Maths paper that I just can't seem to get my head around :eek3: .

    Find the values of x in the range 0<x<360 (degrees) satisfying the equation :

    4sinx = 3cosx .

    Now, I thought tanx=sinx/cosx so I did 4/3 to get 1.33 and then put in tan-1(1.33 but after having a look on the markscheme this is their answer

    4sinx−3cosx= 0 ⇒

    sinx/cosx = 3/4 ⇒ tanx=0.75 ⇒ tan-1(0.75 then all the relevant values.


    Now where I get confused is, sinx/cosx is 4/3 surely and I don't understand how they have switched it to make 4 the denominator and 3 the numerator?

    Can someone please explain?

    Thanks
    Offline

    1
    ReputationRep:
    \displaystyle\frac{4sinx}{3cosx}  =1

    tanx=\frac{3}{4}
    • Thread Starter
    Offline

    0
    ReputationRep:
    Hi,

    Thanks but that still doesn't make any sense?

    I thought tanx=sinx/cosx

    therefore 4sinx/3cosx would equal tanx 4/3?
    Offline

    2
    ReputationRep:
    (Original post by abcmaths)
    Hi,

    Thanks but that still doesn't make any sense?

    I thought tanx=sinx/cosx

    therefore 4sinx/3cosx would equal tanx 4/3?
    4sinx = 3cosx
    sinx = 3/4cosx
    sinx/cosx = 3/4
    tanx = 3/4
    • Thread Starter
    Offline

    0
    ReputationRep:
    Thanks I completely understand it now
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: February 7, 2010
The home of Results and Clearing

1,353

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.