What is the distance between the center of the circle x ^ 2 + y ^ 2-4x + 2Y + 1 = 0 and the straight line X-Y + 1 = 0

What is the distance between the center of the circle x ^ 2 + y ^ 2-4x + 2Y + 1 = 0 and the straight line X-Y + 1 = 0

Center of circle (2, - 1), using the distance formula from point to line
D = | ax0 + by0 + C | / root (a ^ 2 + B ^ 2) = 4 / root 2 = 2 times root 2

Given the circle C: (x-1) 2 + (y + 1) 2 = 1, then the distance from the center of the circle C to the origin of the coordinate o is___ ．

From the circle C: (x-1) 2 + (y + 1) 2 = 1, we can get the center of the circle C (1 -, 1); | OC | = 12 + (- 1) 2 = 2

Given the equation x ^ 2 + y ^ 2-4x + 4Y + 4 = 0 of a circle, the shortest distance and the longest distance from the point on the circle to the origin are obtained

The equation of the circle (X-2) ^ 2 + (X-2) ^ 2 = 4, the center of the circle (2,2), the radius is 2
The shortest distance from the point on the circle to the origin is 2 √ 2-2, and the longest distance is 2 √ 2 + 2

The coordinates of the point nearest to the origin on the circle x2 + y2-4x-4y + 4 = 0 are known

Set as a, a (2 √ 2-2,2 √ 2-2)