Results 1 to 5 of 5

Math Help - FInd exact value of the expression Sec(arctan -5/12)

  1. #1
    Junior Member
    Joined
    Jun 2008
    From
    San Diego
    Posts
    26

    FInd exact value of the expression Sec(arctan -5/12)

    Hey guys i want to know if i am correct here

    let y=arctan(-5/12)

    sec y= 13/12 or 65 degrees

    is this correct
    Follow Math Help Forum on Facebook and Google+

  2. #2
    o_O
    o_O is offline
    Primero Espada
    o_O's Avatar
    Joined
    Mar 2008
    From
    Canada
    Posts
    1,407
    Yep, except you might not want the 65 degrees as your answer as that is obviously not an exact answer and is not even equivalent to your expression.

    \sec\left[ \arctan \left( -\frac{5}{12}\right) \right] should be unitless.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by NoAsherelol View Post
    Hey guys i want to know if i am correct here

    let y=arctan(-5/12)

    sec y= 13/12 or 65 degrees

    is this correct
    The correct answer is NOT an angle .....

    \sec\left[ \arctan \left( -\frac{5}{12}\right) \right] = \frac{13}{12} OR {\color{red}-} \frac{13}{12}.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor Mathstud28's Avatar
    Joined
    Mar 2008
    From
    Pennsylvania
    Posts
    3,641
    Quote Originally Posted by NoAsherelol View Post
    Hey guys i want to know if i am correct here

    let y=arctan(-5/12)

    sec y= 13/12 or 65 degrees

    is this correct
    \sec\left(\arctan(x)\right)=\sqrt{x^2+1}
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor
    Joined
    Apr 2005
    Posts
    1,631
    Quote Originally Posted by NoAsherelol View Post
    Hey guys i want to know if i am correct here

    let y=arctan(-5/12)

    sec y= 13/12 or 65 degrees

    is this correct
    If y = arctan(-5 /12),
    then, tan(y) = -5/ 12
    So, y is an angle whose tan value is -5 /12.

    tan = (opposite side)/(adjacent side) = opp/adj

    So, for angle y above,
    opp = -5
    adj = 12
    The hypotenuse---hyp---then is sqrt[(-5)^2 +(12)^2] = 13

    sec = hyp/adj
    So, sec(y) = 13/12 -----you got that right.

    -----------------------

    If y = arctan(5/(-12)),
    Then, opp = 5, adj = -12, hyp = 13

    sec(y) = 13/(-12) or -(13/12)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Exact Value of the expression without a calculator
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: June 22nd 2011, 01:59 AM
  2. Exact Value of arctan (-2)
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: January 10th 2011, 02:25 PM
  3. Exact Value of Expression
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: March 30th 2009, 05:48 AM
  4. Find Exact Value of Each Expression
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: August 29th 2008, 05:15 AM
  5. Simplify arctan expression
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: September 15th 2007, 03:51 PM

Search Tags


/mathhelpforum @mathhelpforum