Lines and Planes in 3D: Equations, Examples, and Tangent Planes

Learn how points, direction vectors, and normal vectors build lines and planes in three dimensions. Work through equations, intersections, distances, and tangent-plane normals with 10 visual slides and 12 practice problems with solutions.

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Partial Derivatives: Formulas, Examples, and Applications

Partial derivatives measure how a multivariable function changes when one input varies and the others are held constant. This complete Calculus 3 lesson develops limit definitions, trace curves, first and mixed partials, tangent planes, the multivariable chain rule, linear approximation, rigorous counterexamples, and solved practice problems.

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