Hi,

I have a maths exam tomorrow, so I would be grateful for any help!

So here it is:

Let f(t) = a cos b(t-c) + d(I understand that this refers to the transformation)

when t = 3, there is a maximum value of 29,

when t = 9, there is a minimum value of 15.

Find the value of a.

I got as far as:

29 = a cos 3t

15 = a cos 9t

Is that right? And how should I find a?

Thanks!