making equations of simple harmonic functions.and.?

1.How do you write an equation for a simple harmonic motion given that the amplitude is the 5 centimeters and the frequency is 1/pie cycles per second..? I have to assume that the maximum displacement occurs when t = 0 .

2. how do i find the exact value of cos(174degrees)cos(84 degrees) + sin(174 degrees)sin(84 degrees)..?

3. Solve the equation 2 - 2 sin x = 1, 0degrees is less then or equal to x and less then or equal to 360 degrees..

answear is in degrees how to get the answear the comma 0 <orequal to x < orequal to 36o is confusing me.