Let's get an equation for the line....we have that
y = -2(x - 3) + 5 simplify
y = -2x + 6 + 5
y = -2x + 11 (1)
We can let (3, 5) be the center of a circle with a radius of AB
So we have the circular equation
(x - 3)*2 + ( y - 5)^2 = (6√5)^2 sub (1) into (2) for y and we have that
(x - 3)^2 + ( -2x + 11 - 5)^2 = 180 simplify
(x -3)^2 + ( 6 - 2x)^2 = 180
x^2 - 6x + 9 + 4x^2 - 24x + 36 = 180
5x^2 - 30x + 45 = 180
5x^2 -30x - 135 = 0 divide through by 5
x^2 - 6x - 27 = 0 factor
( x - 9) ( x + 3) = 0
Set both factors to 0 and solve for x and we have that
x = 9 and x = -3
Using the equation of the line
y = -2(9 -3) + 5 y = -2(-3 - 3) + 5
y = -12 + 5 y = 12 + 5
y = - 7 y = 17
So....the two possible endpoints for B are ( -3, 17) and ( 9, -7)
Here's a graph : https://www.desmos.com/calculator/viyvhipurq