A circle has the equation x2+y2=5x^2 + y^2 = 5x2+y2=5
Write down the coordinates of the centre of the circle.
Write down the exact length of the radius of the circle.
P P\,P is the point (1,2) on the circle x2+y2=5x^2 + y^2 = 5x2+y2=5
Work out the equation of the tangent to the circle at PPP.