Results 1 to 2 of 2

Math Help - Trig

  1. #1
    Member
    Joined
    Oct 2007
    Posts
    209

    Trig

    Find tan (x/2) if sin x = 3/5 with 90<x<180degrees

    I don't understand how is there an answer.
    because x=arcsin (3/5), which is .64 and that isn't in the 2nd quadrant...
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Apr 2008
    Posts
    1,092
    Quote Originally Posted by Linnus View Post
    Find tan (x/2) if sin x = 3/5 with 90<x<180degrees

    I don't understand how is there an answer.
    because x=arcsin (3/5), which is .64 and that isn't in the 2nd quadrant...
    You are correct that arcsin will return only values in the 1st and 4th quadrants, because it is a function and functions must have only one value of output for each value of input. However, there is an angle x in the 2nd quadrant such that \sin x = \frac{3}{5}. Its value is 180 degrees minus the value you get for arcsin.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Compute Trig Function Values, Solve Trig Equation
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: September 8th 2011, 08:00 PM
  2. Replies: 7
    Last Post: April 15th 2010, 09:12 PM
  3. Replies: 6
    Last Post: November 20th 2009, 05:27 PM
  4. Replies: 1
    Last Post: July 24th 2009, 03:29 AM
  5. Trig Equations with Multiple Trig Functions cont.
    Posted in the Trigonometry Forum
    Replies: 4
    Last Post: April 7th 2008, 06:50 PM

Search Tags


/mathhelpforum @mathhelpforum