10.3: 2, 3, 8
    10.5: 11
    12.3: 1, 2, 7, 8, 9, 10, 11

12.3:
    1)  Use:

    to show that the circular function with period and phase difference can be written as a combination of pure sine and cosine functions of the same period:

    Show that and .

    To start with, lets use the sum trig identity to rewrite our function:

    Now if we let and we have:

    10.5: 11

    12.3: 1, 2, 7, 8, 9, 10, 11