Trigonometry Graphs
To draw the graphs for sin, cos, and tan, you must use the quadrantal angles. For the tan curve you also need
to remember that tan 45° = 1.
0
90
180
270
sin
cos
tan
Steps to drawing the basic trig. graphs:
1) Count each box as 15°. So you count 6 boxes for each 90 degree interval (0-90, 90-180, 180-270, and
270-360).
2) Use the exact value from the quadrantal angle chart to plot your points on the graph.
3) After plotting the points on the graph, draw a smooth curve to connect the points. DO NOT DRAW
STRAIGHT LINES!!!!!
4) Label your graph with the appropriate equation.
Example #1: Graph y = sin θ
[θ (theta) is sometimes used instead of x. You treat them the same.]
Example #2: Graph y = cos θ
Example #3: Graph y = tan θ

Remember: When drawing the tan curve, you need to include that tan 45° = 1 in addition to the
quadrantal angles.
Amplitude and Period
y = A sin Bx
Amplitude: The height of the graph. In the above equation, the amplitude is controlled by “A” .
Example #4: Graph y = 2 sin θ
Period: The time it takes to go through one cycle and then start over again. In the equation at the top of the
page, the period is controlled by “B”.
Example #5: Graph y = sin 2θ (Since we changed “B” to 2, there will be 2
complete curves between 0° and 360°
Practice:
1) y = 3 cos θ
2) y = tan 3θ
3) y = 4 sin 2θ