why are TI graphing calculators still so expensive

[d b]

(08-11-2016 01:55 PM)Joe Horn Wrote:  From the article:

Quote:"Perpendicular lines don't look perpendicular because the window is a rectangle," one Texas-based math teacher told Mic.

Why is somebody who doesn't know how to change the plot window settings on a graphing calculator teaching with it? <facepalm>

None of his students have showed him how to do that yet.