Can someone please help me work out what software is being used to generate these diagrams.

Question

Function Plot

Trigonometry

Circle

Answer 1

I suggested FREE GeoGebra, and here you can see how 'powerful' is this software solution when we need to plot graphs of some functions:

Next, we are able to find the intersection points of a given graphs, the area of a region between them, and many more. Also, it is important that GeoGebra is multi-platform dynamic mathematics software.