[sf-lug] py class: need math help!

[Alex Kleider]

I need some help with what seems to be elementary math/trig:

Take a pencil and piece of paper and try to stay with me:

We start at C for center of circle and based on that center 
draw an arc of radius r from A to B such that the angle ACB is equal to twice theta
bisect our angle with a line from C to D at the midpoint of the arc.
it intersects AB at E
Now I've been assuming that triangles DEB and BEC were similar and therefore
knowing ED and EB I was solving for CB (the radius.)
i.e : tan theta = ED / EB
   and radius = CB = EB/sin theta

This is my attempt to solve the next series of problems.
I'd appreciate any help.