Geometry Expressions

Slope App

We create an app which allows the user to drag a right angled triangle over a picture, and thus estimate the slope of a cliff face.

We draw a triangle on top of our picture.

Animation: drawing a triangle on a photo of a cliff

Constrain one line to be horizontal and the other to be vertical.

Constrain the coordinates of two points, leaving them as variables.

Animation: constraining the legs to be horizontal and vertical, and the coordinates of two points

Measure the lengths of the horizontal and vertical lines and the slope of the slant line.

Animation: measuring the legs and the slope of the slanted side

When we create the app, we specify that the coordinates variables should be specified by dragging.

Animation: creating the app, with the coordinates set by dragging

Here is the resulting app.