$BD^2 = x^2 + (y - 1)^2 + z^2 = 2$ - Treasure Valley Movers

Understanding the Equation $BD^2 = x^2 + (y - 1)^2 + z^2 = 2$: Geometry, Interpretation, and Applications

When you encounter the equation $BD^2 = x^2 + (y - 1)^2 + z^2 = 2$, it may initially appear as a straightforward algebraic expression, but it represents a rich geometric concept with implications in geometry, physics, and coordinate transformations. This article explores the meaning, derivation, and significance of this equation, making it a valuable resource for students, educators, and professionals working in mathematics, engineering, or computer graphics.

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What Does $BD^2 = x^2 + (y - 1)^2 + z^2 = 2$ Represent?

The equation $x^2 + (y - 1)^2 + z^2 = 2$ defines a 3-dimensional sphere in the Cartesian coordinate system $(x, y, z)$, centered at $(0, 1, 0)$ with a radius of $\sqrt{2}$. The term $BD^2$ suggests a squared distance—specifically, it represents the squared distance from a point $(x, y, z)$ to the point $B = (0, 1, 0)$, scaled such that $BD^2 = 2$ describes all points at a fixed distance of $\sqrt{2}$ from $B$.

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Breaking Down the Components

• Center at $(0, 1, 0)$: The $(y - 1)^2$ term shifts the center along the $y$-axis, positioning it one unit above the origin.
  - Spherical Surface: The standard form of a sphere’s equation is $(x - x_0)^2 + (y - y_0)^2 + (z - z_0)^2 = r^2$, matching perfectly here with center $(0, 1, 0)$ and radius $\sqrt{2}$.
  - Equal to 2: Restricting the distance to exactly $\sqrt{2}$ makes this a surface, not an entire volume—an important distinction in 3D modeling and physics.

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Visualizing the Sphere

Imagine a sphere centered slightly off the origin, elevated along the $y$-axis to the point $(0, 1, 0)$. From every point precisely $\sqrt{2}$ units away from this center, the equation holds. This surface appears as a symmetrical, smooth balloon centered vertically in the space.

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Mathematical Derivation: Starting from a Point-to-Point Distance

Let’s derive the equation step-by-step:

Let $P = (x, y, z)$ be any point in 3D space.
The distance $BD$ from $P$ to the fixed point $B = (0, 1, 0)$ is given by the Euclidean distance formula:

\[
BD = \sqrt{(x - 0)^2 + (y - 1)^2 + (z - 0)^2} = \sqrt{x^2 + (y - 1)^2 + z^2}
\]

Squaring both sides gives:

\[
BD^2 = x^2 + (y - 1)^2 + z^2
\]

Setting $BD^2 = 2$, we get the final form:

\[
x^2 + (y - 1)^2 + z^2 = 2
\]

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Applications of This Equation