Circles and tangents

By the end you’ll be able to

• Use the equation of a circle in forms such as $(x-a)^2+(y-b)^2=r^2$ and the expanded general form.
• Determine the centre and radius of a circle from its equation, including by completing the square.
• Find the equation of a tangent to a circle at a given point.
• Use the fact that a radius is perpendicular to a tangent to solve coordinate geometry problems.