Calculate the angle between the x axis and the y axis.
(1,0,0)T · (0,1,0)T = 0. Therefore the x and y axis are orthogonal. (As we expected).
The previous problem was particularly easy to visualize, and particularly easy to calculate. Let us try something harder: The picture shows two vectors:
The angle between the two vectors is not 90°, and so is harder to see than in the previous example. Click on the right and left rotate buttons to get a better idea of the angle.