The third derivative
[src]
/ 2 2 2 2 \
| cos (x) 3*sin (x) 3*cos (x)*sin (x)|
|-1 + ----------- - ----------- + -----------------|*cos(x)
| 2 2 2 |
| 1 - sin (x) 1 - sin (x) / 2 \ |
\ \1 - sin (x)/ /
-----------------------------------------------------------
_____________
/ 2
\/ 1 - sin (x)
$$\frac{\left(-1 - \frac{3 \sin^{2}{\left(x \right)}}{1 - \sin^{2}{\left(x \right)}} + \frac{\cos^{2}{\left(x \right)}}{1 - \sin^{2}{\left(x \right)}} + \frac{3 \sin^{2}{\left(x \right)} \cos^{2}{\left(x \right)}}{\left(1 - \sin^{2}{\left(x \right)}\right)^{2}}\right) \cos{\left(x \right)}}{\sqrt{1 - \sin^{2}{\left(x \right)}}}$$