Hi,
unless someone corrects me its somethings like.........
Radius = Vsquared / GxTan angle of bank
V squared is TAS converted from Knots into metres then squared, conversion factor is 0.514 approx. G = load factor, use 10.
therefore
Radius = (300squared x 0.514 ) / 10 x tan 45deg. = 2377
closest answer 2381.
good luck
paul