Triangle in circle -1

Construction

1.Draw line EO, where O is circle center.
2.Draw line FA parallel to EO.
Point A, on the circle,
is one of vertices of triangle in question.
3. Draw line AD. The point M of intersection of AD and EO is the midpoint of side BC of triangle AD.
4. Side BC is perpendicular to line EO.

[Graphics:Images/DEF-2.jpg]