AP EAMCET Engineering 2011 Solved Paper

Equation of sphere,
x2+y2+z2+2x−2y−4z−19=0 .......(ii)
and equation of plane
x+2y+2z+7=0 .......(ii)
centre of the sphere (−1,1,2) and radius of the sphere
R=√1+1+4+19
=√25=5
Now, p= perpendicular distance from the centre to the plane
p=

|−1+2+4+7|

√1+4+4

=

12

√9

=

12

3

=4 In ΔAOC
R2=p2+r2
⇒ r2=R2−p2
⇒ r2=25−16=9
⇒r=3