Find the locus of a pt in polar form

[VHAHAHA]

the question is showed below
i know that x=rcos θ and y= rsinθ and x^2 + y^2 = R^2
but i just dun know how to find the locus is polar form
any clue ?

 

[AJ Bentley]

All you have to do is to find the position of the ring in terms of r and θ.
It's easy to get r in terms of t and also θ in terms of t.

That gives you two formulae - you just have to eliminate 't' between them.

 

[VHAHAHA]

All you have to do is to find the position of the ring in terms of r and θ.
It's easy to get r in terms of t and also θ in terms of t.

That gives you two formulae - you just have to eliminate 't' between them.

u mean

r= (u)t
and
θ= (w)t

so
rw=uθ and then rw-uθ=0 ??

actually i have listed this equ but i just don't believe my self
i feel that i have missed something

 

[AJ Bentley]

Ya got to have faith.

If you're not sure, draw the locus (path).
Note that rω = θu can be written as r = kθ where k is a constant - that's easy to plot.

 

[VHAHAHA]

Ya got to have faith.

If you're not sure, draw the locus (path).
Note that rω = θu can be written as r = kθ where k is a constant - that's easy to plot.

the path will be something like a @ ??

 

[AJ Bentley]

The Spiral of Archimedes.

http://www.mathwords.com/s/spiral.htm

 

[VHAHAHA]

ya i got it, thx