Important convention: Angles are always measured anticlockwise from the positive x-axis.
Drag the angle slider along to see how the tangent graph is generated. Consider how this follows on from the first applet. Why is it useful to use the unit circle (radius 1)? Consider why the triangle has been extended outside of the unit circle.
What is the period of the tangent graph? How can you tell by looking at the graph/unit circle?
Why is the amplitude not applicable for the tangent graph? How can you tell by looking at the graph/unit circle?