Divide the circle's equation by 2 to get the standard form x^2 + y^2 + x/2 - y/2 + 5/2 = 0. Applying the tangent length formula L = sqrt(x1^2 + y1^2 + 2gx1 + 2fy1 + c) for the point (0,0), we get L = sqrt(0 + 0 + 0 - 0 + 5/2). This simplifies directly to sqrt(5/2).