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

    2
    ReputationRep:
    Tanx=cosx

    -pi <x <pi
    • Community Assistant
    Offline

    15
    ReputationRep:
    Community Assistant
    (Original post by ramshahk)
    Tanx=cosx

    -pi <x <pi
    Whats the identity for tanx?
    Should be able to form a quadratic from that.
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by an_atheist)
    Whats the identity for tanx?
    Should be able to form a quadratic from that.
    -pi <x <pi
    How would you form a quadratic
    • Community Assistant
    Offline

    15
    ReputationRep:
    Community Assistant
    (Original post by ramshahk)
    -pi <x <pi
    How would you form a quadratic
    tanx=sinx/cosx
    in the question tanx=cosx, so sinx/cosx=cosx. If we bring the cosx up, we get sinx=(cosx)^2. What other identity can you use?
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by an_atheist)
    tanx=sinx/cosx
    in the question tanx=cosx, so sinx/cosx=cosx. If we bring the cosx up, we get sinx=(cosx)^2. What other identity can you use?
    The question says -pi <x<pi
    • Community Assistant
    Offline

    15
    ReputationRep:
    Community Assistant
    (Original post by ramshahk)
    The question says -pi <x<pi
    That's a limit on the range of values x can take. In theory there are an infinite number of points where tanx=cosx.
    For the minute, ignore it.
    • Thread Starter
    Offline

    2
    ReputationRep:
    (Original post by an_atheist)
    That's a limit on the range of values x can take. In theory there are an infinite number of points where tanx=cosx.
    For the minute, ignore it.
    Okaay
    Offline

    16
    ReputationRep:
    Tanx = Cosx

    Sinx / Cosx = Cosx

    Sinx = Cos^2x

    Sinx = 1 - Sin^2x

    Sin^2x + Sinx - 1 = 0

    Let y = sinx

    y^2 + y - 1 = 0

    i think this is how u do it but i probably made a mistake somewhere


    Posted from TSR Mobile
    • Community Assistant
    Offline

    15
    ReputationRep:
    Community Assistant
    (Original post by DamnDaniel2)
    Tanx = Cosx

    Sinx / Cosx = Cosx

    Sinx = Cos^2x

    Sinx = 1 - Sin^2x

    Sin^2x + Sinx - 1 = 0

    Let y = sinx

    y^2 + y - 1 = 0

    i think this is how u do it but i probably made a mistake somewhere


    Posted from TSR Mobile
    Looks good. Just trying to avoid giving this guy the answer on a plate, since it will help him more in the long run.
    Offline

    16
    ReputationRep:
    (Original post by an_atheist)
    Looks good. Just trying to avoid giving this guy the answer on a plate, since it will help him more in the long run.
    Yh I realised after! So sorry

    Should've given the first 2 steps or just the identity they should've used and then left it there


    Posted from TSR Mobile
 
 
 
  • 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
    Brussels sprouts
    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.