The figure shows a sinusoidal wave at a given instant. Which points are in the same phase?

$A$ plane progressive wave is given by $y = 2 \cos 6.284(330t - x)$. What is the period of the wave?

The equation of a simple harmonic progressive wave is given by $y=A \sin (100 \pi t-3 x)$. Find the distance between $2$ particles having a phase difference of $\frac{\pi}{3}$.

The wave equation is $y = 0.30 \sin (314t - 1.57x)$ where $t, x$ and $y$ are in second,meter and centimeter respectively. The speed of the wave is ..... $m/s$.

The displacement equations of two waves are given as ${y_1} = 10\sin \left( {3\pi t + \frac{\pi }{3}} \right)$ and ${y_2} = 5(\sin 3\pi t + \sqrt 3 \cos 3\pi t)$. What is the ratio of their amplitudes?

Two waves are given by $y_1 = a \sin(\omega t - kx)$ and $y_2 = a \cos(\omega t - kx)$. The phase difference between the two waves is