A general tangent function has the form;
y=Atan(Bx−C)+D
A changes the amplitude of the graph by stretching it in the vertical direction. B changes the period of the graph by stretching it in the horizontal direction. C tells you how far to move the graph in the x direction, and D tells you how far to move the graph in the y direction.
First we should start with a basic tangent function. This is a graph of the function y=tan(x) on the interval [−π,2π].
Here A and B are 1 and C and D are 0. Lets change the amplitude of our graph by including the −3 from above. The negative will flip the image and the 3 will stretch it vertically, so a graph of −3tan(x) would look like the red below.
Now we can change the C value to get our final graph. The π4 term will move the graph π4 radians to the right, so our final graph will look like the red below.