Any line with a gradient of 3 will be parallel to \(y = 3x + 7\). Two examples are \(y = 3x - 2\) and \(y = 3x + 11.6\). Find the equation of a straight line that is perpendicular to \(y = 2x + 1\).

This determines the gradient of the required line. Use B\((6,3)\) and \(m\). The perpendicular bisector passes through the midpoint of AC. This determines the point on the required line.