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Orbital mechanics 1
How do planets move? An introduction to orbital mechanics and the work of Johannes Kepler.
Practice interesting area and circumference problems.
Sal introduces ellipses and shows how their standard equation relates to their center and radii (ellipses have two radii: major and minor).
Find the center and major and minor radius of an ellipse given its equation.
Click and drag either foci to change orbit. You can also mouseover the terms below for definitions.