The graphs of the functions of the three trigonometic ratios, y = sin x, y = cos x and y = tan x are shown below.
The xaxis units are radians. Remember: 180° = π radians.
These graphs are called periodic functions because the pattern repeats itself over and over. The frequency with which it does this is called the period of the function.
The amplitude of the graph is the distance between the xaxis and the highest point on the graph.
y=sin xThe period of the graph is 2π or 360°. The amplitude of the graph is 1. There are no asymptotes. The domain is R the set of real numbers. The range is 
Click Here to see the graph of y = sinx being formed. 
y=cos xThe period of the graph is 2π or 360°. The amplitude of the graph is 1. There are no asymptotes. The domain is R the set of real numbers. The range is 
Click Here to see the graph of y = cosx being formed. 
y=tan xThe period of the graph is π radians or 180°. There are asymptotes every π radians or 180°. The domain is R the set of real numbers except where the asymptotes occur. The range is the real numbers R 
Click Here to see the graph of y = tanx being formed. 
Transformations of the Basic Trigonometric Functions
More complicated trigonometric functions of the form y = Asin(Bx − C) + D and y = Acos(Bx − C) + D can be sketched by transforming the basic graphs shown above. Each of the variables A, B, C and D change either the shape or position of the basic graphs.
Type of function

Feature changed

Transformation required

Examples

y = A sinx y = A cos x 
the amplitude

The basic graph is compressed or stretched along yaxis by scale factor A. The new ampitude is A 

y = sin Bx y = cos Bx 
the period

The basic graph is compressed or stretched along xaxis by scale factor B. The new period is 360° ÷ B 

y = sin(x − C) y = cos(x − C) 
the position

The basic graph is translated along the xaxis by C. For (x − 30°) the graph moves 30°to the right. 

y = sinx + D y = cos x + D 
the position

The basic graph is translated along the yaxis by D. If D is positive the graph moves UP 
Putting it all together...
Sketch the graph of y = 3sin(2x  60) + 1 
3 
Changes amplitude to 3 
2

Changes period to 360 ÷ 2 = 180°  
2x  60

Moves graph right by 60 ÷ 2 = 30°  
+1

Moves graph up 1 
The graph looks like this:
It is unlikely that you will be asked to perform all four of these transformations for one graph!