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NDA2012MathematicsThree Dimensional GeometryActual

What is the diameter of the sphere x^2+y^2+z^2-4 x+6 y-8 z-7=0

Options

  1. A4 units
  2. B5 units
  3. C6 units
  4. D12 units

Correct answer

C. 6 units

Step-by-step solution

Compare with aligned & x^2+y^2+z^2+2 u x+2 v y+2 w z+d=0 & u=-2, v=3, w=-4, d=-7 & radius = u^2+v^2+w^2-d & = 4+9+16+7 & = 36 =6 . aligned

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