cos(θ) is the x-coordinate of the point P and, sin(θ) is the y-coordinate of the point P. This applet shows how the graphs of sin(θ) and cos(θ) follow directly from the definition of these functions.

The wavelength is the length of one wave, 40 cm. The amplitude is the height of the wave, 10 cm. A displacement-time graph shows how the displacement of one point on the wave varies over time.

This circle has the centre at the origin and a radius of 1 unit. The point P can move around the circumference of the circle. At point P the \(x\)-coordinate is \(\cos{\theta}\) and the \(y ...