### Solving trigonometric functions

Hi

I have quite complex trigonometric function to solve, but sage only solves sin(alpha) and leaves some cos(alpha) on the other side. It is hard to explain, but see the link below:
http://sage.ehasa.org:8080/home/pub/2/

Update: the things in question:

```
var('x,p,k,y,g,v,alpha')
A=-(g/(2*(v*cos(alpha))^2))
k=((v*cos(alpha))/(v*sin(alpha)))
p=(g*x)/(v*sin(alpha)^2)
B=(k+p)
C=(y-k*x-p*x^2)
(A+B+C).solve(alpha)
```

(It would be also nice to generate dynamic function where I put v, x and y. Tried something but I wasn't able to do that, help please?)