Skip to main content\(\newcommand{\R}{\mathbb{R}}
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A three dimensional plot with axes labeled
\(x\text{,}\) \(y\text{,}\) and
\(z\text{.}\) A sphere is drawn in gray with two points on the sphere highlighted in red and green. At each of the highlighted points, a titled plane is shown, in red and green, such that the plane is tangent to the sphere at the highlighted point. Each highlighted point has a vector drawn perpendicular to the surface and pointing away from the origin.