Wheel theoretical problem

[Leah5467]

Hi,my question is as following:

so i don't get why the solution is this for c?

Thank you!

 

[Harry_the_cat]

h'(t) is the rate of change of height with respect to time.
Descending means h'(t) =-0.5.

h'(t) = ab cos (bt) where a and b are given.
So sub h'(t) = -0.5 and solve for t.

 

[Leah5467]

Thank you! I have a question:How to reach abcos(bt)? It is a reverse function but i don't really know how to reverse that function.

 

[Harry_the_cat]

No, it is the derivative of h(t) = a sin bt + 2. Have you done some calculus yet?

 

[Leah5467]

Nope,so i think i don't have to do this part first. Thank you!

 

[Harry_the_cat]

It looks like you have been given a past paper before you have finished the course. That's fine, but means you won't be able to do some parts of the questions with multi-parts. This is IB SL, right?