1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Inverse trig functions

  1. Jan 28, 2010 #1
    Evaluate the following expressions. Your answer must be in radians.

    a) arctan(-(sqrt3)/3)

    b) arctan((sqrt3)/3)

    c) arctan(-sqrt3)

    What I got are:

    a) 5pi/6

    b) pi/6

    c) 2pi/3

    Do I got these answers right?
  2. jcsd
  3. Jan 28, 2010 #2


    User Avatar
    Science Advisor
    Homework Helper

    Hi shiri! :smile:

    (have a pi: π and a square-root: √ :wink:)

    Yes and no.

    The tangents of those angles are the numbers given.

    But "arctan" mean the principal value, which is usually taken to be between -π/2 and π/2 …

    see http://en.wikipedia.org/wiki/Arctan" [Broken].

    (The reason why that range is chosen (and not the [0,2π) for arccos and arcsin) is because tan goes smoothly from -∞ to ∞ in that range.)

    You've chosen the range from 0 to 2π (of course, if your professor told you to do so, ignore wikipedia and me :wink:).
    Last edited by a moderator: May 4, 2017
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook