Draw a table containing x and y values.
Insert the values in the equation y=sin(x + π/2), y = sin(x + 3π/2), etc.
In the equation y=sin(x + π/2), let us assume the value for x as 1 and 2.
When, x=1
Y = sin (1 + π/2)
Y = sin (1 + 3.14/2)
Y =0.54
When, x=2
Y = sin (2 + π/2)
Y = sin (2 + 3.14/2)
Y = -0.42
Continue doing this until the values for y start repeating. You know you have the complete revolution of a wave when the values for y start repeating. One complete revolution will include the highest and the lowest points of the wave.
Put all the values in the table you created in Step 1, and locate the highest number in the table. The amplitude of your wave is the value of the highest number.
Locate the highest number in the table. This is the measure of the amplitude of your wave.
Plot the points on the x and y coordinates drawn. Draw a line to join these points. This is your wave. The highest or the lowest peak of the line is the amplitude of your wave.