Results 1 to 2 of 2

Math Help - identity

  1. #1
    Member
    Joined
    Sep 2005
    Posts
    136

    identity

    verify the following identitie:
    sin2θ/sin θ - cos2θ/cos θ = secθ
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,848
    Thanks
    321
    Awards
    1
    Quote Originally Posted by bobby77 View Post
    verify the following identitie:
    sin2θ/sin θ - cos2θ/cos θ = secθ
    \frac{sin(2\theta)}{sin(\theta)} - \frac{cos(2\theta)}{cos(\theta)}

    = \frac{2sin(\theta)cos(\theta)}{sin(\theta)} - \frac{2cos^2(\theta) - 1}{cos(\theta)}

    = 2cos(\theta) - \left (2 cos(\theta) - \frac{1}{cos(\theta)} \right )

    = \frac{1}{cos(\theta)}

    = sec(\theta) (Check!)

    -Dan
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. the i*pi=ln(-1) identity
    Posted in the Pre-Calculus Forum
    Replies: 7
    Last Post: August 1st 2010, 04:26 AM
  2. identity
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: July 24th 2010, 06:50 AM
  3. Identity
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: February 11th 2010, 08:32 AM
  4. An identity
    Posted in the Math Challenge Problems Forum
    Replies: 0
    Last Post: April 7th 2009, 10:22 PM
  5. identity
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: January 21st 2009, 09:40 PM

Search Tags


/mathhelpforum @mathhelpforum