Trig graphs help please :)

Hey guys,

Please could someone be kind enough to help me with the question in the attachment. Any help will be appreciated.
Thanks

Just derive it and set y' = 0
Edit: rip answer

Heads up: you mean differentiate, not derive. :-)

Thanks, and I didn't know we were talking about transformations, woops x)

Surely you've learnt function transformations? This is just of $\cos x$ shift by $\frac{\pi}{2}$ radians to the right. It will have the same minimum and maximum values as $\cos x$ but the x coordinates of these extrema will be shift to the right as well. As will the roots.

I actually haven't learnt function transformations I did have a lesson the graphs but not any transformations. I'm not sure why the teachers skipped that :/

That's very weird. Anyhow, $\cos(x - \frac{\pi}{2})$, why don't you let $y = x - \frac{\pi}{2}$ and then all you have is $\cos y$ which you know how to find the roots of, the maximum and minimum, etc... once you've got all of those, then just back-substitute.

Thank you, I understand that bit now. However do I change the limits for part iii) ?
And if we do then does it become 0 + pi/2 < X < 2pi + pi/2 ??

Yes.

Yay, thank you

You can do it your way as well.