A sinusoidal function has an amplitude of 1.3 units, a period of 1800° , and a maximum at (0,0). Determine an equation of the function.
a. y=1.3cos ( x/5 )+1.3
b. y=1.3cos ( x/5 )
c. y=1.3cos ( X/5 )-1
d. y=cos ( x/5 )-1.3