MATLAB: Find vertices and plot triangle in Matlab

Question

The vertices of triangle is given in

tri = [1 2 2 1; 1 2 -2 1]

I see that tri has 4 columns and 2 rows, but how does they define the vertices?

What are the vertices defined in the tri and how to plot them in Matlab?

Answer 1

 plot(tri(1,:), tri(2,:))