Geometry: triangulation for measuring a lot/yard

[Dave Britten]

What, one mention of Casio and I scare everyone away???

I did a bit more playing around with the Prime and various TIs, and skimmed through the manuals, but the only brand that seems to let you manually enter coordinates/lengths/angle measures/etc. for various parts of your drawing is Casio. The Prime and Nspire have the advantage that you can drag and resize things in real-time (with Casio's geometry, you drag a point/line/box outline, and the whole drawing updates only when you finish moving). But Casio lets you do constraint-based geometry by entering known measurements, or forcing two or more line segments to stay equal in length. On the Prime you can at least go to the symbolic view and define objects using specific coordinates, but I don't see a way to define objects based on their other measurements. All of them let you include specific measurements directly in the drawing, and automatically update them as you change the drawing.

So the HP and TI geometry apps seem better suited for exploring and playing with geometry as you learn the concepts, and Casio is easier to use for something resembling very light CAD or surveying. (You can skip the TI-84 Cabri Jr. though. It's unusably slow.)