1. ## Parametrics Representations

Coming to a close to my prelim year, extension maths generally went alright but the I still don't get parametrics... any tricks to these?

Until now I figured that there's a bunch of subsititutions to do, but how do you recognise them?

2. ## Re: Parametrics Representations

Can you post some examples of the sort of questions you are struggling with and your current thought process with these questions?

This would make it much easier to help .

3. ## Re: Parametrics Representations

Just do more questions parametrics is legit the same process every single time

4. ## Re: Parametrics Representations

Originally Posted by pikachu975
Just do more questions parametrics is legit the same process every single time
Yeah parametrics will pretty much ask you the same thing especially for Year 11 3U (e.g. equation of tangent, normal etc.)

Just remember that if its a tangent or normal question to differentiate the equation and then sub in the x-coordinate of the point in question to find the gradient and then use point gradient formula from there.

Other questions they can ask (from memory) is normally just asking you to prove that certain lines are parallel (show that they have same gradient) and that certain lines are equal (you can use distance formula). They can also ask you stuff on focal chords - just remember that pq=-1 for focal chords for your typical parabola. This is all from memory so I might be wrong.

5. ## Re: Parametrics Representations

Originally Posted by captainhelium
Yeah parametrics will pretty much ask you the same thing especially for Year 11 3U (e.g. equation of tangent, normal etc.)

Just remember that if its a tangent or normal question to differentiate the equation and then sub in the x-coordinate of the point in question to find the gradient and then use point gradient formula from there.

Other questions they can ask (from memory) is normally just asking you to prove that certain lines are parallel (show that they have same gradient) and that certain lines are equal (you can use distance formula). They can also ask you stuff on focal chords - just remember that pq=-1 for focal chords for your typical parabola. This is all from memory so I might be wrong.
Don't have to derive equation of a tangent it's on formula sheet.

NOTE: make sure to state "FROM FORMULA SHEET" because some markers don't know it exists and will be like "how'd you get this"

6. ## Re: Parametrics Representations

Originally Posted by captainhelium
- just remember that pq=-1 for focal chords for your typical parabola.
What a lot of people don't realise is that this is only true if you are using standard parametric equation. There have been a couple of HSC questions that have given non-standard equations. In that case, the other formulas on the sheet are also wrong.

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