# Mathematics Extension 1 Exam Predictions/Thoughts (1 Viewer)

#### Idkwhattoput

##### Member
$\bg_white \noindent Note that it is not generally true that if \cos A = \cos B, then \cos \left(\frac{\pi }{2}-A\right) = \cos\left(\frac{\pi}{2}-B\right).$
I stated the domain of both alpha and x0, to justify using the composite angle. Will I lose marks (if any marks at all are lost for doing that)?

#### Idkwhattoput

##### Member
I stated the domain of both alpha and x0, to justify using the composite angle. Will I lose marks (if any marks at all are lost for doing that)?
In a bubble I considered the case where the composite angles do not work, and I received alpha=pi (which is not true). But it turns out you're supposed to arrive at alpha=0 to prove that case not true. I must have made a silly mistake, but seeing as how I don't think me showing the other case to be false was necessary, would I still get full marks?

#### psmao

##### Member
for the last question what I did was
i) equalling the differentiations of the two functions (as they have a common tangent at x0)
ii) consider squaring both side and use sin^{2}x+cos^{2}x=1 to convert into the square of sin are equal
then we notice that x0-\alpha and x0 can't be positively equal since ASTC and the range of \alpha,x0
iii) use ii) to replace x0-\alpha and consider ASTC but it doesn't work here again due to the range of \alpha, x0, so the only possible situation is the even property of cos.

#### InteGrand

##### Well-Known Member
I stated the domain of both alpha and x0, to justify using the composite angle. Will I lose marks (if any marks at all are lost for doing that)?
Depends what you said exactly I think.

#### psmao

##### Member
what raw mark would you guys reckon for a state rank? Is 69/70 possible?
I was brain damaged during the exam I think, for the last mc I literally forgot horizontal line tests and vertical line tests rippppp

#### Idkwhattoput

##### Member
what raw mark would you guys reckon for a state rank? Is 69/70 possible?
I was brain damaged during the exam I think, for the last mc I literally forgot horizontal line tests and vertical line tests rippppp
Lol. I also got 69 with q10 wrong (misread it horribly even though i checked it like 5 times). I think 100 raw definitely AND a great 4u mark are necessary for state rank