Hey there! Sign in to join this conversationNew here? Join for free

Find all the values of x in the range 0° ≤ x ≤ 180° satisfying 4tan(x) + 7sin(x) = 0 Watch

Announcements
    • Thread Starter
    Offline

    0
    ReputationRep:
    Hello everyone. I can't figure out how to solve the following:

    Find all the values of x in the range 0° ≤ x ≤ 180° satisfying

    4tan(x) + 7sin(x) = 0


    Thanks for the help!
    Offline

    15
    ReputationRep:
    (Original post by Callanb)
    Hello everyone. I can't figure out how to solve the following:

    Find all the values of x in the range 0° ≤ x ≤ 180° satisfying

    4tan(x) + 7sin(x) = 0


    Thanks for the help!
    You could write tanx = sins/cosx and factorize.
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by RichE)
    You could write tanx = sins/cosx and factorize.
    thanks for the reply riche, i understood that i should use that identity but I am completely stuck on how to actually make anything useful of it.
    Offline

    15
    ReputationRep:
    (Original post by Callanb)
    thanks for the reply riche, i understood that i should use that identity but I am completely stuck on how to actually make anything useful of it.
    Like I said, factorize. Both expressions now have a sinx in them.
    • Political Ambassador
    • Welcome Squad
    Offline

    10
    ReputationRep:
    (Original post by Callanb)
    thanks for the reply riche, i understood that i should use that identity but I am completely stuck on how to actually make anything useful of it.
    u will have a sinx/cosx -7sinx.. then u can multiply it with cosx..
    Offline

    2
    ReputationRep:
    Name:  IMG_0287.PNG
Views: 23
Size:  78.4 KB

    Solve further
    Offline

    1
    ReputationRep:
    (Original post by Mo3yman)
    Name:  IMG_0287.PNG
Views: 23
Size:  78.4 KB

    Solve further
    You can't cancel all the sinx. You have to take the sinx out as it is common for both. So you get
    Sinx(7cosX + 4)=0
    SinX=0. CosX=-4/7
    • Political Ambassador
    • Welcome Squad
    Offline

    10
    ReputationRep:
    (Original post by Ackashh05012911)
    You can't cancel all the sinx. You have to take the sinx out as it is common for both. So you get
    Sinx(7cosX + 4)=0
    SinX=0. CosX=-4/7
    exactly
    • Community Assistant
    Offline

    20
    ReputationRep:
    (Original post by Ackashh05012911)
    You can't cancel all the sinx. You have to take the sinx out as it is common for both. So you get
    Sinx(7cosX + 4)=0
    SinX=0. CosX=-4/7
    If there is ever one rule that I have learned:
    Never cancel, just factor it out.
    You more than likely lose a solution through division or cancellation if it isn't necessary.
 
 
 
  • 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
    Should Spain allow Catalonia to declare independence?
    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.