Find the critical value tc for a 90% confidence when the sample size is 22

Could someone with number 1 and 2

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?

A. s.a.! this is a similarity in right triangles. next (solve for x)a.) 12b.) 5c.) 12.5d.) [tex] 6\sqrt{3} [/tex]