Question

Let (3, 4, –1) and (–1, 2, 3) are the end points of a diameter of sphere. Then the radius of the sphere is equal to

• A. 1
• B. 2
• C. 3
• D. 9

Answer 1

Answer: (C)

3

Answer 2

$d = \sqrt { ( - 1 - 3 ) ^ { 2 } + ( 2 - 4 ) ^ { 2 } + ( 3 + 1 ) ^ { 2 } }$ = $\sqrt { 16 + 4 + 16 }$ $= \sqrt { 36 } = 6$

So, radius