Evaluating a line integral ( vector calculus) Evaluate the line integral,
$$\int_C |y|\, {\rm d}s,$$
Where the curve $C$ is  the  is given by the equation $(x^2+y^2)^2=29^2(x^2-y^2)$
What I tried.
I recognize this as a scalar valued function, hence I know that I must first parameterize the curve C. What I did was to change it to polar coordinates and getting $r^4=29^2(r^2\cos(t)-r^2\sin(t))$ and then simplifying it to get $r=29(\cos2t)^{0.5}$ and hence getting a parameterization  of $r(t)=(29(\cos2t)^{0.5}\cos(t),29(\cos2t)^{0.5}\sin(t))$ but I'm unsure whether my parametrisation is correct , could anyone please explain. Thanks

Hint:
Your curve looks like this:

And it has the following solutions:
$$y = -\sqrt{-2 x^2-29 \sqrt{8 x^2+841}-841}/\sqrt{2}$$
$$y = \sqrt{-2 x^2-29 \sqrt{8 x^2+841}-841}/\sqrt{2}$$
$$y = -\sqrt{-x^2+29/2 \sqrt{8 x^2+841}-841/2}$$
$$y = \sqrt{-x^2+29/2 \sqrt{8 x^2+841}-841/2}$$
This should allow you to split the integral into a form like this:
$\int_a^b|f|\,dx$
