You are given a circle with center **O** and radius **r**. Two chords of the circle, **AB** and **CD** , are equal and parallel to each other. **E** is a point between **B** and **D** on the perimeter of the circle.
You are given radius of the circle **r** and length of the chord **AB**. You have to calculate **angle AEC**.

This is a companion discussion topic for the original entry at https://toph.co/p/geometry-is-fun-huh