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Need help with Cosine question

  • 06-04-2011 8:52pm
    #1
    Scram
    Registered Users, Registered Users 2 Posts: 683 ✭✭✭


    im revising for a maths test
    and below line has be totaly lost;

    -0.5194=cos(thetha)
    Ans:
    121.29 degress = thetha

    What am i missing?


Comments

  • #2
    Michael Collins
    Moderators, Science, Health & Environment Moderators Posts: 1,852 Mod ✭✭✭✭Michael Collins


    Scram wrote: »
    im revising for a maths test
    and below line has be totaly lost;

    -0.5194=cos(thetha)
    Ans:
    121.29 degress = thetha

    What am i missing?

    Take the inverse cos of both sides:

    [latex] \displaystyle \cos(\theta) = -0.5194 [/latex]
    [latex] \displaystyle \cos^{-1}(\cos(\theta)) = \cos^{-1}(-0.5194) [/latex]
    [latex] \displaystyle \theta = \cos^{-1}(-0.5194) = 121.27^\circ [/latex]


  • #3
    Scram
    Registered Users, Registered Users 2 Posts: 683 ✭✭✭Scram


    Thank you so much:)


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