An object undergoes simple harmonic motion along an x axis with a period of $0\mathrm{.}25$ s and

amplitude of $35$ mm$.$ Its position is x $=13$ mm when t $=0$ s$.$ Keep $0$ i $2$

$($a$)$ Write an equation showing the object$$s displacement with all the variables identified. Hint:

two possible initial phases $($use radians$),$ why?