Copy of Circle Geometry - angles from a chord
A illustration of the properties of the angles drawn from the ends of a chord in a circle.
Circle Theorems http://www.geogebratube.org/student/c89/m1462/yryy
Two important results are the equality of the angles at the circumference and their connection to the angle at the centre.
A special case that you are often expected to know is the result when the angle at the centre is 180.
When AB becomes a diameter and you have a semi-circle.
What is significant about the angle at the circumference in this case?