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

Alex Kleider a_kleider at yahoo.com
Sun Oct 5 18:10:31 PDT 2008

```--- On Sun, 10/5/08, jim <jim at well.com> wrote:

>
>    so what is the goal?
>
>
>
>
> On Sun, 2008-10-05 at 09:47 -0700, Alex Kleider wrote:
> >
> > 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.
> >
I'm sorry for not being clear :
the goal is :
if one wants ED and EB to be specific lengths (say 20 and 50 respectively)
How to calculate the radius and the angle to give this.

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