4 A circle has equation \(( x - 5 ) ^ { 2 } + ( y - 2 ) ^ { 2 } = 20\).
- State the coordinates of the centre and the radius of this circle.
- State, with a reason, whether or not this circle intersects the \(y\)-axis.
- Find the equation of the line parallel to the line \(y = 2 x\) that passes through the centre of the circle.
- Show that the line \(y = 2 x + 2\) is a tangent to the circle. State the coordinates of the point of contact.