Find the equation of the circle whose centre is (2, 3) and which touches the line 3x - 4y - 1 = 0.

Find the equation of a circle whose centre is (1,2) and radius 2.

Find the equation of the circle whose centre is (4, 5) and which passes through the centre of the circle x ^2 + y ^2 + 4x -6y - 12 = 0

Find the equation of a circle whose centre is the origin and passes through the point (2,-4).

Find the equation of the circle whose radius 4 and which is concentric with the circle x ^2 + y ^2 + 2x - 6y = 0.

write down the equation of the circle whose centre is the point (-2, 3) and radius is of lenght of 5 units.

Write down the equation of the circle whose centre is the point (2, -3) and radius is 5 units.

Find the equation of the circle of radius a, in the first quadrant, which touches both the axes.

Find the equation of the ellipse whose vertices are (0,+-6) and eccentricty is 1/3.

Find the equation of the circle of radius 5 units which is concentric with the circle x ^2 + y ^2 + 2x - 4y = 0

Find the equation of the circle concentric with the circle x ^2 + y ^2 - 8x + 12y + 15 = 0 and passing through the point (5, 4).