Question

What is the smallest positive phase constant which is equivalent to 7⋅5 π?

Answer 1

Equation of the wave: y = A sin(kx − ωt + Φ)
Here, A is the amplitude, k is the wave number, ω is the angular frequency and Φ is the initial phase.

The argument of the sine is a phase, so the smallest positive phase constant should be
$$\begin{gathered} \sin \left(7.5\mathrm{\pi }\right)=\sin \left(3\times 2\mathrm{\pi }+1.5\mathrm{\pi }\right) \\ =\sin \left(1.5\mathrm{\pi }\right) \end{gathered}$$
Therefore, the smallest positive phase constant is 1.5π.