Calculating Coordinate of B in Sinusoidal Wave Equation

[dekoi]

At a certain instant, a point A is at the origin and a point B is the first point on the x-axis that is 60° out of phase. What is the coordinate of B?

The equation of the wave is given as:
y = (15.0 cm)cos(0.157x-50.3t)

 

[SpaceTiger]

At a certain instant, a point A is at the origin and a point B is the first point on the x-axis that is 60° out of phase. What is the coordinate of B?

The equation of the wave is given as:
y = (15.0 cm)cos(0.157x-50.3t)

Hint:

$$y = A cos(kx+\omega t)$$

where A is the amplitude of the wave, k is the wavenumber, and $\omega$ is the angular frequency. The latter two are given by

$$k=\frac{2\pi}{\lambda}$$
$$\omega=\frac{2\pi}{T}$$

where T and $\lambda$ are the period and wavelength. What fraction of a wavelength is between the two points?