Key learning points

1. There are many circle theorems so it is important to be clear about each one
2. Extra lines can be added to a diagram to help determine which theorem to use
3. Some problems require the use of more than one theorem

Keywords

• Tangent - A tangent of a circle is a line that intersects the circle exactly once.

• Chord - A chord is any line segment joining two points on the circumference of a circle.

• Perpendicular - Two lines are perpendicular if they meet at right angles.

• Equidistant - Points A and B are equidistant from a third point C if the distance AC is equal to the distance BC.

Common misconception