Find the length of the tangent from (1,2)(1, 2)(1,2) to the circle x2+y2+4x−6y+1=0x^2 + y^2 + 4x - 6y + 1 = 0x2+y2+4x−6y+1=0.
222
5\sqrt{5}5
333
10\sqrt{10}10