If the radius of the sphere S is 8 units, what is the value of k?
Answer
The correct answer is A: −15. For sphere x² + y² + z² − 4x − 6y − 12z + k = 0, center is (2, 3, 6) and radius = √(4 + 9 + 36 − k) = √(49 − k). Given radius = 8, so 49 − k = 64, giving k =…
A.−15✓ Correct
B.7
C.10
D.15
Explanation
For sphere x² + y² + z² − 4x − 6y − 12z + k = 0, center is (2, 3, 6) and radius = √(4 + 9 + 36 − k) = √(49 − k). Given radius = 8, so 49 − k = 64, giving k = −15.
💡 Practice unlimited NDA PYQs + AI-tracked progress on each topic. Sign up free →
More Three Dimensional Geometry - Sphere questions