Sorry for bothering you again but this is rather (very?) urgent. I have one question that I want to ask and if you could help me, it would be greatly appreciated. Also, would you be able to do them in radian measure and give the exact answers (eg. without decimals).:

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Given f(x) = 2sinx - cosx

Write in the form of Asin(x + a)

I've managed to do this one with the answer being:

square root 5 (x + arctan -0.5)

Find the maximum value of 2sinx - cosx and the corresponding values of x

Okay, I've found that the maximum value is square root 5 (using my trusty calculator) but I'm quite stuck on finding the corresponding values of x. Could you perhaps provide a starting point of some sort or guide me through this one?

Find the least positive value of p such that f(x) = f(x + p)

Now this is the one I need urgent help on. I have absolutely no idea how to go about this one. I assume thepwould mean the period. Do I simply find the period ofsquare root 5 (x + arctan -0.5)?

I tried some working out but am uncertain about it:

2sinx - cosx = f(x + p)

2sin(x + p) - cos(x + p)

2(sinxcosp + cosxsinp) - (cosxcosp - sinxsinp)

2(sinx) - cosx

?!

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Thankyou VERY much guys. All help is definitely appreciated.