I’ve always loved tree rings, in part because the word dendrochronology fascinated me a child. This lovely cross-section evokes so many mathematical ideas: concentricity, network theory, and polar representations, to name a few.
Appreciation Numbers
12/04/14 — Happy Permutation Day!
Today we celebrate another Permutation Day! I call days like today permutation days because the digits of the day and month can be rearranged to form the year.
Celebrate Permutation Day by mixing things up! Try doing things in a different order today. Just remember, for some operations, order definitely matters!
Appreciation
A Zometool Thanksgiving
While cleaning up after a successful group build, a colleague and some students had fun making a little Thanksgiving tribute in Zometool.
Resources Teaching Technology
Derivatives of Vector Functions
One way to think of a curve in the plane (or in space) is as a collection of terminal points of vectors whose initial points are all at the origin. The vectors are given by a vector-valued function.
For example, the parabola shown at right can be thought of as the graph of the vector-valued function
I’ve created a Desmos demonstration that shows how graphs of vector-valued functions are related to their vectors (shown in blue), and how the derivative of a vector-valued function is related to both difference vectors and tangent vectors. You can access the demonstration here.
You can find more of my Desmos demonstrations here.
Appreciation Geometry Photography
Math Photo: Undersea Rose Curve
I can’t look at this lovely jellyfish without seeing a four-petal rose curve in the polar plane.
