Find an equation of the sphere with center (-3, 2 , 5) and

radius 4. What is the intersection of this sphere with the

yz-plane.

## Answer

(x+3)^2+(y-2)^2+(z-5)^2=4^2=16 is the equation of the

sphere.

yz-plane means x = 0

=>9+(y-2)^2+(z-5)^2=16

=>(y-2)^2+(z-5)^2 = 7

Therefore the intersection of this sphere with the yz-plane is a

circle of radius sqrt(7) and centre at (0,2,5).