Warming up!
Theo Jansen is the man who reinvented the wheel by constructing "strandbeests"
as seen here on TED.
Construct a GeoGebra Strandbeest ↓
...or just make some polygons ↓
... or find points in triangles
Start with two triangles. Use some tools (which tools?) to do this ↑
The blue intersectionspoints are not the same in the two different cases.