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Math Help - tanB

  1. #1
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    tanB

    Given tan A = 8 and tan (A + B) = -17/6, what is the exact value of tan B?

    I got tan B = 13/27 but the textbook tells me the answer is
    0.5. How do I get 0.5?
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  2. #2
    MHF Contributor Calculus26's Avatar
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    Using the formula for tan(a+b) = [tan(a) +tan(b)]\[1-tan(a)tan(b)]


    -17/6 = [8 + tan(b)]/[1-8tan(b)]

    -17[1-8tan(b)] = 6[8+tan(b)]

    -17 +136 tan(b) = 48 + 6tan(b)

    130tan(b) = 65

    tan(b) =.5
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  3. #3
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    To clear...

    Quote Originally Posted by Calculus26 View Post
    Using the formula for tan(a+b) = [tan(a) +tan(b)]\[1-tan(a)tan(b)]


    -17/6 = [8 + tan(b)]/[1-8tan(b)]

    -17[1-8tan(b)] = 6[8+tan(b)]

    -17 +136 tan(b) = 48 + 6tan(b)

    130tan(b) = 65

    tan(b) =.5
    To clear the fractions, you multiplied both side by 6, right?
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  4. #4
    A riddle wrapped in an enigma
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    Quote Originally Posted by magentarita View Post
    To clear the fractions, you multiplied both side by 6, right?
    Hi magentarita,

    To clear the fractions, Calculus26 multiplied both sides by 6(1 - 8 tan B).
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  5. #5
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    got it

    Quote Originally Posted by masters View Post
    Hi magentarita,

    To clear the fractions, Calculus26 multiplied both sides by 6(1 - 8 tan B).
    I understand now. Thanks.
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