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: Find the exact value

  1. Jun 26, 2008 #1
    1. The problem statement, all variables and given/known data
    Find the exact value of the function:
    tan(cos^-1 0.5)

    2. Relevant equations

    I used this formula: y=sin^-1=sin y=x for the first part, how do I solve the second part of the problem tanx (x)?

    3. The attempt at a solution
    x=cos^-1 (0.5)
    N= pi/3
    Then I tried tanx(x)=
    I'm stuck
  2. jcsd
  3. Jun 26, 2008 #2

    D H

    User Avatar
    Staff Emeritus
    Science Advisor

    Why did you change x to N?
  4. Jun 26, 2008 #3
    [tex]\tan{(\cos^{-1}\frac 1 2)}=\tan x[/tex]

    [tex]x=\cos^{-1}\frac 1 2[/tex]


    Ok, you have x? So your equation just ... [tex]\tan x[/tex] ... solve for tangent!
  5. Jun 26, 2008 #4
    Don't know? good question, but I see that I just have to plug in pi/3 into tanx (x)
  6. Jun 27, 2008 #5


    User Avatar
    Science Advisor

    [tex]tan(x)= tan(\pi/3)= \frac{sin(\pi/3)}{cos(\pi/3)}[/itex]
    Surely you know [itex]sin(\pi/3)[/itex] and [itex]cos(\pi/3)[/itex]!
    Last edited by a moderator: Jun 27, 2008
  7. Jun 27, 2008 #6
    The first line of ivy should be:
    [tex]tan(x)= tan(\pi/3)= \frac{sin(\pi/3)}{cos(\pi/3)}[/itex]
  8. Jun 27, 2008 #7


    User Avatar
    Science Advisor
    Homework Helper

    There's another way to do this. Draw a right triangle that has a angle of cos^(-1)(1/2) in it. E.g. hypotenuse 1 and adjacent side 1/2. Use Pythagoras to find the missing side. Now find tan by opposite/adjacent.
  9. Jun 27, 2008 #8
    Thank you!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook