a changes the amplitude of the wave by a factor of a. (for example is the same as except the peak and minimum values are 2 and -2, not 1 and -1.)
b changes the frequency of the sine wave by a factor of b. ( for example has twice the frequency of . So it only takes radians (or 180 degrees) for a full wave, instead of (or 360 degrees)).
c translates the graph along the x axis to the left by c places.
d translates the graph along the y axis upwards by d places.