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Find the slope of the tangent at the given angle theta

  1. Mar 22, 2016 #1
    1. The problem statement, all variables and given/known data
    Find the slope of the tangent line to the give polar curve at the point specified by the value of theta R = 1/θ, θ=π

    2. Relevant equations
    ##\frac{(dr/dθ)sinθ + rcosθ}{(dr/dθ)cosθ - rsinθ}##


    3. The attempt at a solution
    The derivative of r is -1/θ2

    Then plugging things into the formula I get
    ##\dfrac{\dfrac{-1}{θ^{2}}sinθ +\dfrac{1}{θ}cosθ}{\dfrac{-1}{θ^{2}}cosθ -\dfrac{1}{θ}sinθ}##

    then i take out a factor is -1/θ from both the denominator and numerator and get

    ##\dfrac{\dfrac{sinθ}{θ}+cosθ}{\dfrac{cosθ}{θ}-sinθ}##

    then plugging in pi wherever thetha is and doing some math i get that its all equal to pi

    the correct answer is supposed to be -pi

    what am i doing wrong
     
  2. jcsd
  3. Mar 22, 2016 #2

    Samy_A

    User Avatar
    Science Advisor
    Homework Helper

    Check the signs after the step "then i take out a factor is -1/θ from both the denominator and numerator and get"
     
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