Results 1 to 3 of 3

Math Help - Exact Value of the expression without a calculator

  1. #1
    Newbie
    Joined
    Jun 2011
    Posts
    14

    Unhappy Exact Value of the expression without a calculator

    sin(3pi/12)cos(pi/12)+cos(3pi/4)sin(pi/12)


    I tried it like this sqrt2/2 (sqrt2/4+sqrt6/4)+(-sqrt2/2+?
    I'm not sure if how to approach it
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,605
    Thanks
    1573
    Awards
    1

    Re: Exact Value of the expression without a calculator

    Quote Originally Posted by LAPOSH42 View Post
    sin(3pi/12)cos(pi/12)+cos(3pi/4)sin(pi/12)
    \sin(\theta)\cos(\phi)+\cos(\theta)\sin(\phi)=\sin  (\theta+\phi)<br />

    And ~\frac{4\pi}{12}=\frac{\pi}{3}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    May 2011
    From
    Islamabad
    Posts
    94

    Re: Exact Value of the expression without a calculator

    sin(3pi/12) = sin(pi/4) and cos(3pi/4) = -cos(pi/4) so your expression becomes

    sin(pi/4)cos(pi/12) - cos(pi/4)sin(pi/12) = sin[(pi/4) - (pi/12)] => sin(pi/6)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Find Exact Value without Calculator
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: July 11th 2011, 03:26 AM
  2. Please find exact value without calculator
    Posted in the Calculus Forum
    Replies: 3
    Last Post: April 21st 2009, 06:45 AM
  3. Exact Value of Expression
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: March 30th 2009, 04:48 AM
  4. expression calculator
    Posted in the Math Software Forum
    Replies: 0
    Last Post: January 23rd 2009, 06:17 PM
  5. Find Exact Value Without Calculator
    Posted in the Pre-Calculus Forum
    Replies: 9
    Last Post: August 21st 2008, 02:50 PM

Search Tags


/mathhelpforum @mathhelpforum