How do Platonist presentists explain the reality of propagating waves?

For example, would "cos(wt)" simply be a four-term relation between:

(i) an amplitude universal

(ii) a universal instantiating the angle of a right triangle

(iii) a universal expressing the ratio of the adjacent and hypotenuse sides of the triangle in (ii)

(iv) a ratio of the angle in (ii) to 180°

Thus does the Platonist presentist ultimately treat "cos(wt)" as a magnitude, an equivalence relation between (i) and (iv) at the time in question?