Question

Sphere O has a radius of 5 and it's center at the origin. Which of the following points lies inside the sphere?

A.(-1,-2,-4)
B.(-1,3,5)
C.(2,-2,6)
D. (6,2,3)
E.(-5,1,2)

Answer 1

its A

Answer 2

You have to imagine that - pick a point that will be the origin and measure 5 units along each of the three axes of the coordinate system. Any point that is located less than 5 units along the axis lies within the sphere. That is - from -5 to 5. A point that is, say, 6 units from the origin will be outside the sphere. Therefore, answers C and D are the ones that are outside and answers A, B and E are inside the sphere.