How does the **period** of a sine function of the form

change in terms of b? An interactive tutorial using an html 5 applet to investigate the priod of a sine function is presented.

__Interactive Tutorial__

- Press the button 'draw' on the left panel below. Two graphs are shown: a red one corresponding to the function
**h(x) = a sin(x)**and a blue one corresponding to the function**f(x) = a sin(b x)**.

- Use the slider to change the value of
**b**(you may also enter values in the box for b). The period of the blue graph with equation**y = a sin(b x)**changes, that of the red is constant and equal to 2?.

- Keep
**a = 2**(it has no effects on the period) and change**b**using the slider or entering values in the box for parameter b then press the button 'draw'. Use integer numbers ± 2, ± 3, ... for**b**so that it is easier to check the formula for the period : 2? / | b |.(In fact for | b | > 1 and b integer, | b | is given by the number of cycles of the blue graph within one cycle of the red graph).