A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

anonymous

  • one year ago

Lecture 5 - Parametric equations Hi, When the cycloid is first introduced, the position of a point, P, on the circumference is described as (all the following are vectors) OP = OA + BA + BP BP = < -asinTheta, -acosTheta > I don't understand this as I thought x = rcosTheta y = rsinTheta Therefore should the components of BP be, BP = < -acosTheta, -asinTheta >? Thanks

  • This Question is Closed
  1. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yes, for a circle centered at the origin, and measuring theta counter-clockwise from the x-axis, then the points on it circumference have coords \[ x= r \cos \theta \ , y= r \sin \theta \] but in this problem, the angle is measured in a "non-standard" way. specificially |dw:1440521647396:dw|

  2. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Hello Phi, Thanks for replying so quickly. So essentially when going clockwise sin and cos give the opposite coordinates to what they give when going anti-clockwise? Thanks

  3. phi
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    the other difference is we are measuring theta from the line pointing straight-down (i.e. parallel to the negative y-axis). this switches which "leg" is sin and cos (as compared to using the positive x-axis as the start)

  4. anonymous
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    I see. Cheers.

  5. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.