The following data represents the normal monthly precipitation for a certain city.( i will post the table)
draw a scatter diagram of the data for one period. find the sinusoidal function of the form (i will post) that fits the data.

Step-by-step explanation:

Use a sinusoidal function of the form

A is the amplitude, obtain the difference between the highest and the lowest value, and then divide by two:

D is the vertical shift, is equal to the lowest value plus the amplitude:

B is the frequency, being 12 months for each cycle (period T=12) and the relation between the period and the frequency is:

Finally, for C the phase shift, the highest value in a  sine function the highest point is in the first quartes of the period if the period is 12, then this maximum is in x=3. In the data the highest is in x=7, so the phase shift is to the right and equal in value to 4 (C=4).

So:

For the form

multiply C by B to find E ():