The equation of circle with centre (1, -2) and radius 4 cm is :

$x^2 + y^2 + 2x - 4y = 16$ $x^2 + y^2 - 2x + 4y = 16$ $x^2 + y^2 + 2x - 4y = 11$ $x^2 + y^2 - 2x + 4y = 11$

$x^2 + y^2 - 2x + 4y = 11$

We know that, (x -a)2 + (y - b)2 = radius2 Here, a and b are point on centre x and y be any point on circle We have, Centre point are  (1, -2) Radius = 4cm Put the value of  a, b and radius in the above formula, (x-1)2 + (y + 2)2  = 16 = x2 + 1 - 2x + y2 + 4 + 4y = 16 = x2 + y2 - 2x + 4y = 11