Question

Define phase of $S.H.M$ ?

Answer 1

Phase simply means an angular term which represents situation of a particle in SHM at a certain instant

Let one SHM is $x_1=A\sin \omega t$ and another SHM which is differ by first SHM of phase angle $\varphi$ then other SHM is,

$x_2=A\sin (\omega t+\varphi )$

Clear that phase of oscillation is state of oscillation of particle performing SHM.