I am attaching a question and the book answer. I'm fine up to part d but then I'm not. It says sinkt is always 1 but I don't think it is. When t = 3pi it's -1. Am i missing something subtle?
And then they differentiate a to find max a. I did to and I get t/2 = 0, pi, 2pi and I subbed these into a = 4cos(t/2) and got 4 and -4 so I said it's 4. But why have they taken the route that they have.
I'm missing something but what?