A sinusoidal wave can be plotted in a two dimensions. Generally and simply :
As it is being plotted, the horizontal axis (as a straight line) is
x, and the lambda is the wave length after which the wave will be repeated. How can one reach to a sinusoidal wave over a circumference which is not a straight line; Moreover the division of the circumference by the
lambda has to be an integer number. It means:
n is the number of lambda (wave) on the circumference and must be an integer, also,
r is the radii of the circle.