# Angle at the centre of a circle is twice the angle at the circumference

Martin McBride

2020-08-16

For any chord, we can draw two lines to form an angle at the centre of the circle, angle **a**.

We can also draw two lines to form an angle at the circumference, **b**.

The angle at the centre of a circle is twice the angle at the circumference.

This theorem is covered in this video on circle theorems: