Question:medium

The radius of the sphere whose centre is \((4,4,-2)\) and which passes through origin is

Show Hint

If a sphere passes through origin, its radius is the distance between its centre and origin.
  • \(\sqrt2\)
  • \(3\)
  • \(2\sqrt2\)
  • \(6\)
Show Solution

The Correct Option is D

Solution and Explanation

Step 1: Understanding the Concept:
The radius of a sphere is the distance from its center to any point on its surface. If the sphere passes through the origin, then the origin is a point on its surface.

Step 2: Key Formula or Approach:

The distance between two points \((x_1, y_1, z_1)\) and \((x_2, y_2, z_2)\) in 3D space is given by the distance formula: \[ d = \sqrt{(x_2-x_1)^2 + (y_2-y_1)^2 + (z_2-z_1)^2} \] We will use this formula to find the distance between the center of the sphere and the origin. This distance will be the radius.

Step 3: Detailed Explanation:

The center of the sphere is given as \(C = (4, 4, -2)\). The sphere passes through the origin, which is the point \(O = (0, 0, 0)\). The radius \(r\) is the distance between C and O. Using the distance formula: \[ r = \sqrt{(4-0)^2 + (4-0)^2 + (-2-0)^2} \] \[ r = \sqrt{4^2 + 4^2 + (-2)^2} \] \[ r = \sqrt{16 + 16 + 4} \] \[ r = \sqrt{36} \] \[ r = 6 \]

Step 4: Final Answer:

The radius of the sphere is 6, which corresponds to option (D).
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