GRAPHING CIRCULAR FUNCTIONS:
HI..guys....muskan here.... we learned about graphing circular functions couple of days ago...lets take a quick rewiew.


1.Graphing on a cartesian plane is known as ``unrolling``
2.We will plot θ values on x-axis and the trignometric function values at θ on the axis y-axis.
3. One cycle is a portion of the graph from one point to another at which time the graph begins to repeat itself.
4. One period is the lenght of one cycle in either degrees or radians. The period for a sin x or cos x function is 2π/|b| . The period for a tan x is π/|b| .
5.The amplitude is the distance from the middle axis to the highest or lowest point for a sin x or cos x function. A change in amplitude vertically stretches or compresses the basic shape of the curve. The amplitude for sin x or cos x function |a|. The amplitude for a tan x function is unlimited or infinite.
6. Basic equations: y = a sin bx     y = a cos bx     y = a tan bx
7. x represents θ values for x when graphing sin x or cos x.
8. Use quadrant values for x when graphing sin x or cos x.
9. Use quadrant and π/4 values for x when graphing tan x.
10.The tan x function will have asymptotes at quadrantal values where tan x is undefined.
The illustration above only draws the graph of the sine or cosine function for one revolution. However, the domain of these functions is all real numbers. The picture below shows the graphs of sine (orange) and cosine (green) on a larger domain (-3 to 3).

May be this video help to understand better:

                              http://youtu.be/uKyBl1FOaks                               thanks :))