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?