On this book, we have already seen the definitions of sine and periodic functions. It[br]was necessary to talk about periodic functions: when we try to expand the[br]representation of the sine as a function, its graphic is periodic.[br]The next model represents the sine of an angle [math]\alpha[/math] as the [math]y[/math] coordinate of a point on a circle of unitary radious (thus, the hypotenuse of the triangle is also unitary).[br]Use the “play”and “restart” buttons as usual.