If the circle `x^(2)+y^(2)-4x+6y+a = 0` has
radius 4 then find a.

If the circle x^(2) + y^(2) -4x + 6y + a =0 has radius 4, find a.

Find the equation of the circle which is concentric with the circle x^(2) + y^(2) - 6x - 4y- 3 = 0 , and has radius 5.

Consider the circle x^2+y^2-4x-6y-3 = 0 Find the radius of the circle

Find the equation of the circle concentric with the circle x^(2) + y^(2) - 4x + 6y + 4 = 0 and passing through the point (2, -2).

Find the equation of the circle concentric With the circle x^(2) + y^(2) - 4x - 6y - 9 = 0 and passing through the point ( -4, -5).

(i) Find the equation of a circle , which is concentric with the circle x^(2) + y^(2) - 6x + 12y + 15 = 0 and of double its radius. (ii) Find the equation of a circle , which is concentric with the circle x^(2) + y^(2) - 2x - 4y + 1 = 0 and whose radius is 5. (iii) Find the equation of the cricle concentric with x^(2) + y^(2) - 4x - 6y - 3 = 0 and which touches the y-axis. (iv) find the equation of a circle passing through the centre of the circle x^(2) + y^(2) + 8x + 10y - 7 = 0 and concentric with the circle 2x^(2) + 2y^(2) - 8x - 12y - 9 = 0 . (v) Find the equation of the circle concentric with the circle x^(2) + y^(2) + 4x - 8y - 6 = 0 and having radius double of its radius.

Find the equation of the circle concentric with the circle x^(2)+y^(2)-4x-6y-3=0 and which touches the y axis

Find the equation of the circle concentric with the circle x^2 + y^2 - 4x - 6y - 3 = 0 and which touches the y axis

Find the equation of the circle concentric with the circle x^2 + y^2 - 4x - 6y - 3 = 0 and which touches the y axis