Parametric equation for a space curve
With reference to the following image:
the blue curve has trivially a parametrization:
$$(x, y, z) = (costheta, , sintheta, , 0) ; ; ; text{with} ; theta in [0,,2pi)$$
I would like to determine the parametric equations of the red curve, very badly drawn in Paint, where I mean a sinusoidal curve along the blue circumference.
Although I thought about it a lot, I still could not figure out how to derive these parametric equation. Any ideas?
curves parametrization
add a comment |
With reference to the following image:
the blue curve has trivially a parametrization:
$$(x, y, z) = (costheta, , sintheta, , 0) ; ; ; text{with} ; theta in [0,,2pi)$$
I would like to determine the parametric equations of the red curve, very badly drawn in Paint, where I mean a sinusoidal curve along the blue circumference.
Although I thought about it a lot, I still could not figure out how to derive these parametric equation. Any ideas?
curves parametrization
1
It looks like a curve of the form $$ r(theta) = r_0 + A cos{(omega theta )} $$ But it's not very clear what you mean with the hand-drawn curve. Is it supposed to come out of the $z=0$-plane?
– Matti P.
57 mins ago
1
@MattiP.: Yes, it must exit the $z = 0$ plane and have the circumference as the average line.
– TeM
36 mins ago
add a comment |
With reference to the following image:
the blue curve has trivially a parametrization:
$$(x, y, z) = (costheta, , sintheta, , 0) ; ; ; text{with} ; theta in [0,,2pi)$$
I would like to determine the parametric equations of the red curve, very badly drawn in Paint, where I mean a sinusoidal curve along the blue circumference.
Although I thought about it a lot, I still could not figure out how to derive these parametric equation. Any ideas?
curves parametrization
With reference to the following image:
the blue curve has trivially a parametrization:
$$(x, y, z) = (costheta, , sintheta, , 0) ; ; ; text{with} ; theta in [0,,2pi)$$
I would like to determine the parametric equations of the red curve, very badly drawn in Paint, where I mean a sinusoidal curve along the blue circumference.
Although I thought about it a lot, I still could not figure out how to derive these parametric equation. Any ideas?
curves parametrization
curves parametrization
edited 28 mins ago
dmtri
1,4181521
1,4181521
asked 1 hour ago
TeM
415315
415315
1
It looks like a curve of the form $$ r(theta) = r_0 + A cos{(omega theta )} $$ But it's not very clear what you mean with the hand-drawn curve. Is it supposed to come out of the $z=0$-plane?
– Matti P.
57 mins ago
1
@MattiP.: Yes, it must exit the $z = 0$ plane and have the circumference as the average line.
– TeM
36 mins ago
add a comment |
1
It looks like a curve of the form $$ r(theta) = r_0 + A cos{(omega theta )} $$ But it's not very clear what you mean with the hand-drawn curve. Is it supposed to come out of the $z=0$-plane?
– Matti P.
57 mins ago
1
@MattiP.: Yes, it must exit the $z = 0$ plane and have the circumference as the average line.
– TeM
36 mins ago
1
1
It looks like a curve of the form $$ r(theta) = r_0 + A cos{(omega theta )} $$ But it's not very clear what you mean with the hand-drawn curve. Is it supposed to come out of the $z=0$-plane?
– Matti P.
57 mins ago
It looks like a curve of the form $$ r(theta) = r_0 + A cos{(omega theta )} $$ But it's not very clear what you mean with the hand-drawn curve. Is it supposed to come out of the $z=0$-plane?
– Matti P.
57 mins ago
1
1
@MattiP.: Yes, it must exit the $z = 0$ plane and have the circumference as the average line.
– TeM
36 mins ago
@MattiP.: Yes, it must exit the $z = 0$ plane and have the circumference as the average line.
– TeM
36 mins ago
add a comment |
1 Answer
1
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oldest
votes
You can try$$thetamapstoleft(costheta,sintheta,frac{cos(8theta)}8right),$$for instance.
It's exactly what I wanted, thank you! Could you tell me how you managed to understand it?
– TeM
29 mins ago
2
The $z$ coordinate had to be a waving line again, and so I thought about $cos(8theta)$, but then the waves would go too high and too low. That's why I divided by $8$.
– José Carlos Santos
25 mins ago
Perfect! Before closing I also wanted to ask how to get the parametric equations of the red curve if it lay in the $z = 0$ plane. Is it better that I open a new question or change the request?
– TeM
15 mins ago
No need for that. Just consider:$$thetamapstoleft(costheta+frac{cos(8theta)}8,sintheta,0right).$$
– José Carlos Santos
8 mins ago
add a comment |
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1 Answer
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active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
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oldest
votes
You can try$$thetamapstoleft(costheta,sintheta,frac{cos(8theta)}8right),$$for instance.
It's exactly what I wanted, thank you! Could you tell me how you managed to understand it?
– TeM
29 mins ago
2
The $z$ coordinate had to be a waving line again, and so I thought about $cos(8theta)$, but then the waves would go too high and too low. That's why I divided by $8$.
– José Carlos Santos
25 mins ago
Perfect! Before closing I also wanted to ask how to get the parametric equations of the red curve if it lay in the $z = 0$ plane. Is it better that I open a new question or change the request?
– TeM
15 mins ago
No need for that. Just consider:$$thetamapstoleft(costheta+frac{cos(8theta)}8,sintheta,0right).$$
– José Carlos Santos
8 mins ago
add a comment |
You can try$$thetamapstoleft(costheta,sintheta,frac{cos(8theta)}8right),$$for instance.
It's exactly what I wanted, thank you! Could you tell me how you managed to understand it?
– TeM
29 mins ago
2
The $z$ coordinate had to be a waving line again, and so I thought about $cos(8theta)$, but then the waves would go too high and too low. That's why I divided by $8$.
– José Carlos Santos
25 mins ago
Perfect! Before closing I also wanted to ask how to get the parametric equations of the red curve if it lay in the $z = 0$ plane. Is it better that I open a new question or change the request?
– TeM
15 mins ago
No need for that. Just consider:$$thetamapstoleft(costheta+frac{cos(8theta)}8,sintheta,0right).$$
– José Carlos Santos
8 mins ago
add a comment |
You can try$$thetamapstoleft(costheta,sintheta,frac{cos(8theta)}8right),$$for instance.
You can try$$thetamapstoleft(costheta,sintheta,frac{cos(8theta)}8right),$$for instance.
edited 32 mins ago
answered 57 mins ago
José Carlos Santos
150k22121221
150k22121221
It's exactly what I wanted, thank you! Could you tell me how you managed to understand it?
– TeM
29 mins ago
2
The $z$ coordinate had to be a waving line again, and so I thought about $cos(8theta)$, but then the waves would go too high and too low. That's why I divided by $8$.
– José Carlos Santos
25 mins ago
Perfect! Before closing I also wanted to ask how to get the parametric equations of the red curve if it lay in the $z = 0$ plane. Is it better that I open a new question or change the request?
– TeM
15 mins ago
No need for that. Just consider:$$thetamapstoleft(costheta+frac{cos(8theta)}8,sintheta,0right).$$
– José Carlos Santos
8 mins ago
add a comment |
It's exactly what I wanted, thank you! Could you tell me how you managed to understand it?
– TeM
29 mins ago
2
The $z$ coordinate had to be a waving line again, and so I thought about $cos(8theta)$, but then the waves would go too high and too low. That's why I divided by $8$.
– José Carlos Santos
25 mins ago
Perfect! Before closing I also wanted to ask how to get the parametric equations of the red curve if it lay in the $z = 0$ plane. Is it better that I open a new question or change the request?
– TeM
15 mins ago
No need for that. Just consider:$$thetamapstoleft(costheta+frac{cos(8theta)}8,sintheta,0right).$$
– José Carlos Santos
8 mins ago
It's exactly what I wanted, thank you! Could you tell me how you managed to understand it?
– TeM
29 mins ago
It's exactly what I wanted, thank you! Could you tell me how you managed to understand it?
– TeM
29 mins ago
2
2
The $z$ coordinate had to be a waving line again, and so I thought about $cos(8theta)$, but then the waves would go too high and too low. That's why I divided by $8$.
– José Carlos Santos
25 mins ago
The $z$ coordinate had to be a waving line again, and so I thought about $cos(8theta)$, but then the waves would go too high and too low. That's why I divided by $8$.
– José Carlos Santos
25 mins ago
Perfect! Before closing I also wanted to ask how to get the parametric equations of the red curve if it lay in the $z = 0$ plane. Is it better that I open a new question or change the request?
– TeM
15 mins ago
Perfect! Before closing I also wanted to ask how to get the parametric equations of the red curve if it lay in the $z = 0$ plane. Is it better that I open a new question or change the request?
– TeM
15 mins ago
No need for that. Just consider:$$thetamapstoleft(costheta+frac{cos(8theta)}8,sintheta,0right).$$
– José Carlos Santos
8 mins ago
No need for that. Just consider:$$thetamapstoleft(costheta+frac{cos(8theta)}8,sintheta,0right).$$
– José Carlos Santos
8 mins ago
add a comment |
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1
It looks like a curve of the form $$ r(theta) = r_0 + A cos{(omega theta )} $$ But it's not very clear what you mean with the hand-drawn curve. Is it supposed to come out of the $z=0$-plane?
– Matti P.
57 mins ago
1
@MattiP.: Yes, it must exit the $z = 0$ plane and have the circumference as the average line.
– TeM
36 mins ago