Trig Experts and people who know Pre-Calc...help!?

Question

The wheel of a ferris wheel has a 20 m diameter and turns at 4 rpm. Its lowest point is 1.3 m above the ground. Assume that the height (h) is a sinusoidal function of time (t) where t=0 is the lowest point.

a) Write a equation for h.
Answer:
-Okay, so I went through my book and found the equation h=a*sin*w*t+k (I have absolutely no idea what a or w stand for though.)
-Then, I plugged in the numbers and got h=10*sin*4*t+11.3

Is that right? Do you have any idea how to find the equation or explain what I'm doing?

b) Find h at t=10sec.
Answer:
-I figure I would just plug in 10 for t, but how do I solve h=10*sin*40+11.3

Please help! I have pretty much no idea what I'm doing, and I need to understand it for a test. I posted as far as I got, and you don't have to give me the answer. Just tell me what I'm doing...please ?!?

Answer 1

b. divide the cosign on the tangent line