Hello nikita007

Welcome to Math Help Forum!I agree!

The critical points are where the graph of the function has zero gradient. In the case of sine and cosine functions, these will be where the sine and cosine have their maximum and minimum values of +1 and -1 respectively.It then goes on to ask me to find the first five critical points and this is were I'm slightly confused, i have them as; (π/4, 2), (4π/4, 1), (8π/4, 2), (12π/4, 1), (16π/4, 2). My intuition tells me that these are horribly horribly horribly wrong. Could someone please enlighten me on what I am doing wrong here? I just really want a nudge in the right direction. Thank you very much.

In the function , this will be where:

and .

Now you know that when . So work from there, starting with:

Then and

... and so on.

Grandad