Results 1 to 2 of 2

Math Help - Finding a cosine curve from a sine curve?

  1. #1
    Newbie
    Joined
    Apr 2009
    Posts
    18

    Finding a cosine curve from a sine curve?

    Hopefully I posted this in the right spot!

    If I had an equation of a sine curve, and I wanted to find the cosine curve, would I just subtract \frac\pi2 from the horizontal translation value?

    Or rather, if I had a set of data, which, when plotted showed sine curve characteristics, but I actually wanted to find the cosine curve of this data; how would I go about doing that? (hopefully that made sense)

    Thanks.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    -1
    e^(i*pi)'s Avatar
    Joined
    Feb 2009
    From
    West Midlands, England
    Posts
    3,053
    Thanks
    1
    Quote Originally Posted by maybealways View Post
    Hopefully I posted this in the right spot!

    If I had an equation of a sine curve, and I wanted to find the cosine curve, would I just subtract \frac\pi2 from the horizontal translation value?

    Or rather, if I had a set of data, which, when plotted showed sine curve characteristics, but I actually wanted to find the cosine curve of this data; how would I go about doing that? (hopefully that made sense)

    Thanks.
    Nay, you need to add \frac{\pi}{2} to get a horizontal translation left.

    See the spoiler for why this is

    sin(A \pm B)=sin(A)cos(B) \pm cos(A)sin(B)

    Spoiler:
    sin \left(x-\frac{\pi}{2}\right) = sin(x)cos\left(\frac{\pi}{2}\right) - sin\left(\frac{\pi}{2}\right)cos(x)<br />

    cos\left(\frac{\pi}{2}\right)=0 \: \: , \: \: sin \left(\frac{\pi}{2}\right) = 1 \: \: \therefore \: sin \left(x-\frac{\pi}{2}\right)=-cos(x)

    ==============================

    sin \left(x+\frac{\pi}{2}\right) = sin(x)cos\left(\frac{\pi}{2}\right) + sin\left(\frac{\pi}{2}\right)cos(x) = cos(x)<br />
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Finding the period of a trigonmetic sine curve
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: September 25th 2009, 03:27 PM
  2. Period of cosine curve
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: August 13th 2009, 05:31 PM
  3. Sine Curve Simultaneous equation help
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: May 26th 2009, 08:11 AM
  4. Area of a rectangle under a cosine curve?
    Posted in the Calculus Forum
    Replies: 7
    Last Post: June 25th 2008, 05:18 PM
  5. Replies: 8
    Last Post: October 8th 2007, 04:29 PM

Search Tags


/mathhelpforum @mathhelpforum