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Quoting parametric equations in conics questions (1 Viewer)

~ ReNcH ~

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Are we allowed to quote the equation of a tangent/normal/chord of contact etc. in conics questions? Or do we have to derive them?
 

dawso

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if it says derive this equation etc then u hav 2 derive it obviously but if it says somethin other and u can tell by the number of marks given that deriving will be useless (2 marks or so just 2 derive tengent) then dont bother...does this healp?
 

Captain pi

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You must ALWAYS derive equations unless the equation is given in the question or was found in a subquestion of the same Question in each exam.
 

~ ReNcH ~

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Captain pi said:
You must ALWAYS derive equations unless the equation is given in the question or was found in a subquestion of the same Question in each exam.
Ah ic.
I think that was the answer I was searching for :)
 

jumb

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Look at the marks. If It's a 1 mark question, quote the formula. It its a 4 mark, then derive.
 

Captain pi

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jumb said:
Look at the marks. If It's a 1 mark question, quote the formula.
There has never been such a question given in the HSC.

It is important to note that marks are awarded for steps, not for answers. If a one mark question was asked (I maintain, such a question has never been asked), that one mark is probably for the deriving (differentiation and application of point-gradient formular), not the final equation; if you simply quote a formula, bypassing the neccessary step, that's it! You can't be awarded the mark. Similarly, if were to correctly differentiate and apply the point-gradient formula (which is allowed), and then say that c + c = 3c in your working, you will be awarded full marks, because you followed the correct step; the mark cannot be lost for the subsequent error (ISE).

It is imperative that when studying for the Extension 2 HSC exam, you read the markers comments and marking scheme (available at the Board of Studies website) so you have a firm idea of how your paper is likely to be marked.
 
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