Question

15. Find the centre and radius of the circle x2 + y2 + 4 x - 2 y - 4 = 0.
Section-C​

Answer 1

Answer:

Radius of the sphere is r=12+(−1)2+(−2)2+19=5

And center of the sphere is C=(−1,1,2)

Now distance of the given plane from the centre is CP=1+4+4−1+2+4+7=4

Hence radius of the circle is =r2−CP2=3