Help on number 3? Thank you

In one day there are too high tides into low tides and equally spaced intervals the high tide is observed to be 6 feet above the average sea level after six hours passed a low tide occurs at 6 feet below the average sea level in this task you will model this occurrence using a trigonometric function by using x as a measurement of time assume the first high tide occurs at x=0. a. what are the independent and dependent variables? b. determine these key features of the function that models the tide: 1.amplitude 2.period 3.frequency 4.midline 5.vertical shift 6.phase shift c. create a trigonometric function that models the ocean tide for a period of 12 hours. d.what is the height of the tide after 93 hours?

Apossible wavelength for the color blue is 0.000000492 meter. which of the following is a reasonable estimate for this wavelength for the color blue? a. 5 × 10-6 m b. 5 × 107 m c. 5 × 10-7 m d. 5 × 106 m

What is the solution to the system of equations? 10x+3y=8 -9x-y=-20 (11, 1) (1, 11) (–1, 11) (11, –1)'