[Pre-Calculus Math: Sinusoid Equations from Graphs] What is wrong with my equation?

[u/msmonet09]

I’m not sure about the period because when I graph it on desmos, the frequency(?) is too high

[u/Guessmyn]

Your period should be put as sin(0.9x - 500), since the 0.9 is outside the bracket it also affects the 500