find the length of
i use the parametrisation
but what is the range of t?
plot x^(2/3) + y^(2/3) = 1 - Wolfram|Alpha
I suggest you find the arclength for the curve in the first quadrant - the domain for t should be obvious - and then multiply by 4.
You've changed the question so many times, it is hard to be sure what you are asking.
Surely you know that if you are writing x and y in terms of parameter t, then the arclength is given by
That is an integral and there are no partial derivatives.
You said you wanted to use the parameterization y=a(sint)^3, x=a(cost)^3.
In the graph Mr. Fantastic showed you initially, x goes from 0 up to 1 while y goes from 1 down to 0. (He set a= 1.)
For what t is ? For what t is ?