Hello s.a.n.t.a.n.a

Here's the answer to (a). I have to go now. I'll post answers to (b) and (d) later unless someone else does first.

Grandad

(a) Suppose that the equation is .

Since varies between and , the maximum and minimum values of are and .

So: and .

This gives and .

Now is periodic, with period . So:

Also, low tide is at time . So when , . So:

So the equation is