Question

What is the slope of the tangent line of `r=theta-cos((4theta)/3-(3pi)/4)` at `theta=(-2pi)/3`?

Answer 1

See the answer below:

Explanation:

Credits:
Thanks to patrickJMT () and
Math24 (https://www.math24.net/derivatives-polar-functions/)
who helped us to remind the theory on derivative and slope of polar form and thanks to http://www.emathhelp.net/ to help on the check of the results.