For any real number $$t$$, the point $$\left(\frac{8 t}{1+t^2}, \frac{4\left(1-t^2\right)}{1+t^2}\right)$$ lies on a / an

The area of the circle passing through the points $$(5, \pm 2),(1,2)$$ is

The ratio of the largest and shortest distances from the point $$(2,-7)$$ to the circle $$x^2+y^2-14 x-10 y-151=0$$ is

A circle has its centre in the first quadrant and passes through $$(2,3)$$. If this circle makes intercepts of length 3 and 4 respectively on $$x=2$$ and $$y=3$$, its equation is