Find the curve given the tangent

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Homework Help Overview

The problem involves finding a curve \( c(t) \) given its tangent vector \( T(t) = (-\sin(t), \cos(t)) \) at any point on the curve, with the condition that the curve passes through the point \( (0,0) \). The discussion centers around the relationship between the tangent vector and the derivative of the curve.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the relationship between the tangent vector and the derivative of the curve, with one participant attempting to express \( c(t) \) in terms of its components. Questions arise regarding the use of the point \( (0,0) \) and how it relates to the parameter \( t \).

Discussion Status

Some participants have proposed potential forms for \( c(t) \) based on the tangent vector and the initial condition. There is an ongoing examination of the implications of the tangent vector's magnitude and its relationship to the curve's definition. Multiple interpretations of the problem are being explored without a clear consensus.

Contextual Notes

Participants note the challenge of integrating the condition of passing through \( (0,0) \) with the tangent vector's properties. There is also mention of the constant factors that may arise in the general solution for \( c(t) \).

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Homework Statement



Given that the tangent to the curve [itex]c(t)[/itex] at any point on the curve is [itex]T(t) = (-sin(t), cos(t) )[/itex], find [itex]c(t)[/itex] if the curve passes through the point [itex](0,0)[/itex].

The Attempt at a Solution



I try to let
[itex]c(t) = ( x(t), y(t) )[/itex]
Then
[itex]c'(t) = ( x'(t), y'(t) )[/itex]
[itex]| c'(t) | = \sqrt{[x'(t)]^2 + [y'(t)]^2 }[/itex]
And
[itex]T(t) = \frac{c'(t)}{|c'(t)|}[/itex]

However this is complicated and consequently I am not sure how to solve it. I am also not sure how to "use" the point given since (0, 0) correspond the the values x and y respectively rather than t.

Thanks.
 
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If you had c'(t) =<2t,1> then c(t) = <t2+A,t+B> where A,B=constant.


But you have

c'(t)/|c'(t)| = <-sint,cost>

so what is c(t) ? (note that |c'(t)| is just a constant)

At (0,0), t=0. So what is c(t) now?
 
rock.freak667 said:
If you had c'(t) =<2t,1> then c(t) = <t2+A,t+B> where A,B=constant.


But you have

c'(t)/|c'(t)| = <-sint,cost>

so what is c(t) ? (note that |c'(t)| is just a constant)

At (0,0), t=0. So what is c(t) now?

c(t) = (cos(t) + C, sin(t) + K)
t= 0, point is (0,0)

So x(t) = 1 + C = 0, C = -1
And y(t) = 0 + K, K=0

So c(t) = (cos(t) -1 , sin(t) ) ?
 
madachi said:
c(t) = (cos(t) + C, sin(t) + K)
t= 0, point is (0,0)

So x(t) = 1 + C = 0, C = -1
And y(t) = 0 + K, K=0

So c(t) = (cos(t) -1 , sin(t) ) ?

Yes but you forgot out |c'(t)| which is the distance from the center to any tangent. In this case it would just be the same as |T(t)|
 

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