circular orbits using c_move?

hello, I have programmed an object to orbit around another object using the following method.

entity.x = 100*sin(angle);
...
angle += 1;

this is great but it doesnt work with collision detection.
how can i use ent_move to do the same thing?

help needed urgently..

temp.x = 100*sin(angle);
...
angle += 1*time_step;

now move entity to temp vector with c_/ent_move