The cycle and frequency

Wavelength is the distance between one cycle of a wave.
Frequency is the number of complete cycles in one second.
The period of a wave is the time taken for one complete cycle.
Period = 1 / frequency.
            Frequency = 1 / period. [ Hz ]

Sine wave 

 The Unit Circle is a circle with a radius of 1.
 The diagram shows one cycle of a sine wave.
 The sine of the angle θ is represented by the y-value of the point on the unit circle.

Sine wave animation(HTML5)

 white:radius = 1
 red:The location on radius r when being angle θ
 blue:additional line