• Support PF! Buy your school textbooks, materials and every day products via PF Here!

Vector function

  • Thread starter brad sue
  • Start date
Hi,
I do not know how to do this exercise:
Find a vector valued function f that traces out the given curve in the indicated direction.

4x2+9y2=36. a- Counterwise b- clockwise

Thanks
 

quasar987

Science Advisor
Homework Helper
Gold Member
4,771
5
Hi brad,

Here's an idea: First rewrite the equation (which is probably one of an ellipse) as (2x)² + (3y)² = 6². This strangely resembles the equation of a circle. In fact, if we perform the changes of variable w = 2x and z = 3y, then the equation (2x)² + (3y)² = 6² <==> w² + z² = 6² is that of a circle of radius 6 in the w-z plane. You know how to parametrize a circle, right? Then do so and then change back to the variables x & y to find the corresponding parametrisation in the x-y plane.
 
In case you don't remember the parametric equations of a circle are

x=a*cos(t)
y=a*sin(t)

Where a is the radius and as t increase in the positive direction the circle is traced out in a counter-clockwise direction.....

With that and the information quasar987 gave you, you should be able to figure out what to do...

Good luck
 
Townsend said:
In case you don't remember the parametric equations of a circle are

x=a*cos(t)
y=a*sin(t)

Where a is the radius and as t increase in the positive direction the circle is traced out in a counter-clockwise direction.....

With that and the information quasar987 gave you, you should be able to figure out what to do...

Good luck
Thanks to you both
 

Related Threads for: Vector function

  • Posted
Replies
2
Views
1K
  • Posted
Replies
6
Views
2K
  • Posted
Replies
1
Views
1K
  • Posted
Replies
2
Views
994
Replies
4
Views
5K

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top