it's pretty simple lol
14 degrees is the mid point between 9 and 19
so you make that x = 0
at 4am, x = -5 and t=0
at 4pm, x = 5 and t=12
x = 5 cos(pi - pi/12 t)
when x = 0 .......... t = 6
at x = 0, it is 14 degrees
therefore its at 14 degree at 10am
if that made any sense... i'm bad...