Use the general solution model developed to solve the following sinusoidal equations. Note: In some applications of the general solution, results may be negative and the final answer must be adjusted using the period of the function. The following examples were carefully selected to avoid this issue.

1) Seasonal Temperatures: The function shown models the average monthly temperature of the water in a mountain stream, where T(x) is the temperature of the water in month x (x = 1 January). What is the first month of the year with an average temperature 60F?

2) River Discharge Rate: For the months June through January, the average monthly discharge of the La Corcovada River (Venezuela) can be modeled by the function shown, where t represents the months of the year (t = 1 June) and D(t) is the discharge rate in cubic meters/second. What is the first month of the year the discharge rate is 50 m³/sec?

3) Park Visitors: As a home roofer, Marks income fluctuates with the seasons and the availability of work. For the past several years his average monthly income could be approximated by the function shown, where I(m) represents income in month m (m = 1 January). In what month does his average monthly income begin to exceed $4780?