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Parametric equation

  • #1

Homework Statement


Describe motion of a particle w/ position xy


Homework Equations



x=cospi(t) y=sinpi(t)

The Attempt at a Solution


solving for t
t=x/cospi
so y=sinpi(x)/cospi
y=tanpi(x)

interval=at least one at most 2
since tan(x)=0 at pi and 2pi
and this is where the boundaries are so the particle travels from pi and 2pi counterclockwise
but the textbook has a different (but reasonable) answer in that it squares cos pi and
sin pi to equal 1 and uses the circle equation but ends up with the same diagram and
direction. If I went wrong, can you please tell me where I went wrong since my answer
seems legit to me.
 

Answers and Replies

  • #2
195
1
x= cos[tex]\pi[/tex]t
should become
t=[tex]cos^{-1}x[/tex]/[tex]\pi[/tex]
 
  • #3
tiny-tim
Science Advisor
Homework Helper
25,832
249
have some π …

x=cospi(t) y=sinpi(t)

If I went wrong, can you please tell me where I went wrong since my answer
seems legit to me.
Hi evilpostingmong! :smile:

Your initial equations are wrong.

It isn't x=cosπ(t) y=sinπ(t);

it's x=cos(πt) y=sin(πt).

Now try! :smile:

(oh … and here's some π and other things to pack in your bag …)
 

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