Equation of the sphere of radius 3 and tangent to coordinate-planes

Problem
Find the equation of a sphere of radius 3 and tangent to all three coordinate planes if the center is on the first octant.

A.   x2+y2+z29=0
B.   x2+y2+z26x6y6z+18=0
C.   x2+y2+z24x4y4z+12=0
D.   x2+y2+z28x8y8z+14=0

 

A circle has an equation of x^2 + y^2 + 2cy = 0. Find the value of c when the length of the tangent from (5, 4) to the circle is equal to one.

Problem
A circle has an equation of x2+y2+2cy=0. Find the value of c when the length of the tangent from (5, 4) to the circle is equal to one.

A.   5 C.   3
B.   -3 D.   -5