VCE Methods Question Thread!

[b^3]

Just looking at the base angles, sin will be negative in the 3rd and 4th quadrants, with an angle of to the axis, going positive around the unit circle this gives and . The angle is equivalent to going radians in the other direction around the unit circle (clockwise as oppose to anticlockwise), so we have .

EDIT: Beaten.

[Smiley_]

how does the tangent and normal buttons work on the inspire?

[BubbleWrapMan]

Something like

e.g. , the tangent to at .

Not sure if that's what you were talking about lol

[Eugenet17]

The rate of deflection from the horizontal of a 2 m long diving board when
a 70 kg person is x metres from its fixed end is:


c Find the maximum deflection.

Help please!

[revcose]

through CAS, or I got by hand
Substituting x=0 and y=0 in allows you to work out c, and gives you or an equivalent.
at x=-2 or x=0, neither of which are options, so the maximum doesn't has to occur at the other endpoint, x=2. This can be verified with a graph, if you have that option.
substituting x=2 into y gives -0.4
The maximum deflection is 0.4 metres

[Eugenet17]

got it,thanks!

[aestheticatar]

Guys, I'm not too sure about the wording of part d.

Clarification would be sweet as! Awesome

[lzxnl]

Pr(C>292)
C is a normally distributed variable => just integrate.

[Zealous]

For a 1 mark question, if we have errors in our working out, can we still get the 1 mark just from a correct answer? (Although the examiner would probably cringe seeing errors.)

[lzxnl]

No. You lose a mark if you make any mistake.

[Damoz.G]

For a 1 mark question, if we have errors in our working out, can we still get the 1 mark just from a correct answer? (Although the examiner would probably cringe seeing errors.)

No. If it is a one-mark question, they don't care about your working out - They won't even look for it. If you have the answer stated clearly, you got the mark. No working out will help get you 1 mark for a 1-marker. =/

If its like a multiple part question, you get consequential marks. e.g. If you get an equation wrong in part 2c, and then carry that mistake to part 2d, then as long as your working out and/or answer is correct in part 2d, you will get however many marks possible. But you will obviously lose mark(s) for part 2c.

[kinslayer]

Pr(C>292)
C is a normally distributed variable => just integrate.

The distribution of C is not obvious to me from the information given in the question. How is the strength of a chain related to the strength of its four links?

Common sense says that the chain would be as strong as its weakest link, in which case you would just be repeating (a) and (b) again. Is the question missing something, or am I ... ? 

[lzxnl]

I've been told by my maths teacher that if you make a mistake in your working, even if the answer is correct, the examiners take a mark off as it shows misunderstanding of mathematical concepts. Apparently this has happened to lots of people who have the correct answer, but forget what the question wants them to do, so they keep on working, make a mistake, and although they have all the necessary working and the correct answer, they lose a mark because of that mistake.

The distribution of C is not obvious to me from the information given in the question. How is the strength of a chain related to the strength of its four links?

Common sense says that the chain would be as strong as its weakest link, in which case you would just be repeating (a) and (b) again. Is the question missing something, or am I ... ? 

Yeah I misread the question. My bad.

In that case, you would have to find the probability that all four links are stronger than 292.

[SocialRhubarb]

I've been told the same thing as nliu1995 - that even if your answer is correct, you don't get marks if you show incorrect working. Showing no working is fine in a 1 mark question, but you lose marks for incorrect working regardless of the validity of your answer, even in 1 mark questions.

The same applies for questions worth multiple marks. If you show incorrect working and manage, fortuitously, to obtain the correct answer, you still don't get any answer marks if it appears you obtained it with an incorrect method.

Not sure about the consequential point. I think you can get method marks working from an incorrect assumption but not answer marks.

[kinslayer]

Better question -- how do you suppose you will write down the correct answer if your working is incorrect? By accident?