need some calc 3 help .

[mchammer187]

Find the expression for the unit vector tangential to the curve given in cylindrical coordinates by r^2=sin (2*phi)=1, z=0

it seems pretty easy but i havent taken calc 3 since freshman year an now im a junior taking Electromagnetic Field Theory

i tried solving the eq for r in terms of phi and taking that derivative with respect to phi but it gives me
-cot(2*phi)/sqrt(2*phi) and i know thats not right

the answer is + or - (cos (2*phi) * Ar - sin (2*phi) *A phi)

Ar is just the unit vector in the r hat direction

and A phi is just the unit vector in the phi hat direction

any help would greatly be apprectiated

 

[FSUpaintball]

Help with Calc 3? Here's my advice: GET OUT OF CALC 3.


/mesucks at math



nefnefnef

 

[mchammer187]

Originally posted by: FSUpaintball
Help with Calc 3? Here's my advice: GET OUT OF CALC 3.


/mesucks at math



nefnefnef

i took calc 3 2 years ago

 

[Mucman]

Oh man! I can't remember this stuff , I did enjoy the course but I only got a B-, so it's probably better that I don't assist

 

[Omegachi]

hey! i am taking calc 3 now. I think i've learned the formula to do that couple weeks ago. but i kind of forgot it.

 

[Mucman]

Originally posted by: Omegachi
hey! i am taking calc 3 now. I think i've learned the formula to do that couple weeks ago. but i kind of forgot it.

Now I don't feel as bad

 

[UCDznutz]

damn i knew how to do this too. if i could find my book i'd help you out.

 

[brtspears2]

Originally posted by: Omegachi
hey! i am taking calc 3 now. I think i've learned the formula to do that couple weeks ago. but i kind of forgot it.

Thats worse than me. Learn for the quarter, forget it next quarter.