Radius of curvature in terms of normal and semi-parameter

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Salmon states that the radius of curvature of any conic is equal to the cube of the normal divided by the semi-parameter. We create this quantity in Geometry Expressions:

Some simple manipulation shows this is the same expression as in the above example.

Expressions

Name Input
Distance CD Eq Derive Input Maple Input MathML Input Mathematica Input Maxima Input Mupad Input TI-Nspire Input text Input Image
Distance CE Eq Derive Input Maple Input MathML Input Mathematica Input Maxima Input Mupad Input TI-Nspire Input text Input Image
z[0]^3/z[1]^2 Eq Derive Input Maple Input MathML Input Mathematica Input Maxima Input Mupad Input TI-Nspire Input text Input Image