7. The diagram below shows two congruent circles which touch at a single point T.
The circle, centre A, has as its equation x² + y2 - 6x -18y +45 = 0.
The line with equation 2y = x is the common tangent to the two circles through T.
x2 + y2 - 6x-18y+45 = 0
ophon
2y=x
ci
T
O
х
B
(a)
Show algebraically that T has coordinates (6,3).
(b)
Hence establish the the coordinates of B, the centre of the lower circle, and
find the equation of this circle.​