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Current Year 13 thread Mark I (2014-2015)

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Reply 8720

MangoFreak

Original post by Bude8

Doing a maths past paper and this question came up. Never seen such a hideous question before :cry:

Anyone have any ideas? I swear this stuff isn't on the syllabus...

It feels like it's better than it looks...

Express the area of the polygon as

\frac{n(x^2)}{8}\sin\frac{2\pi}{n}

(edited 9 years ago)

Reply 8721

Red Fox

Original post by Bude8

Doing a maths past paper and this question came up. Never seen such a hideous question before :cry:

Anyone have any ideas? I swear this stuff isn't on the syllabus...

Are you stuck on part a or b? or both?

Reply 8722

Enigma Machine

Original post by MangoFreak

It feels like it's better than it looks...

Express the area of the polygon as n(((x^2)/2)sin(2pi/n))?

I should really learn Latex :tongue:

Original post by Red Fox

Are you stuck on part a or b? or both?

Stuck on a, but just had an idea thanks to Mango. I think it'll involve splitting up the polygon into triangles.

Reply 8723

MangoFreak

Original post by Bude8

Stuck on a, but just had an idea thanks to Mango. I think it'll involve splitting up the polygon into triangles.

That was what I was getting at :ahee:

I realise my expression actually took x to be the radius I think so uh ignore that :tongue:

Everything falls into place after that.

(edited 9 years ago)

Reply 8724

Red Fox

Original post by Bude8

Stuck on a, but just had an idea thanks to Mango. I think it'll involve splitting up the polygon into triangles.

Yeah it's pretty easy once you do that. I like the question, I wish A-Level maths had some stuff like this.

(edited 9 years ago)

Reply 8725

MangoFreak

Original post by Red Fox

Yeah it's pretty easy once you do that. I like the question, I wish A-Level maths had some stuff like this.

If A Level exams stopped being predictable, time pressure would **** some of us :tongue:

Reply 8726

L'Evil Fish

Original post by MangoFreak

If A Level exams stopped being predictable, time pressure would **** some of us :tongue:

Lol yeah a question like that under time constraints would probably **** me over

But then again boundaries would be like 40% for top grade

Reply 8727

MangoFreak

Original post by L'Evil Fish

Lol yeah a question like that under time constraints would probably **** me over

But then again boundaries would be like 40% for top grade

That's true, that would be neat :tongue:

Reply 8728

Red Fox

Original post by MangoFreak

If A Level exams stopped being predictable, time pressure would **** some of us :tongue:

Yeah but one or two questions like that wouldn't be too bad, plus grade boundaries would be lower.

Reply 8729

MangoFreak

So is C a good measure of compactness? :holmes:

Reply 8730

Tibbz2

Does it make me crap at maths if I have no idea how to start that question? :redface:

Reply 8731

Enigma Machine

Original post by Red Fox

Yeah it's pretty easy once you do that. I like the question, I wish A-Level maths had some stuff like this.

What do you make of this question?

Wasn't sure on how to do part b

Original post by MangoFreak

So is C a good measure of compactness? :holmes:

Well, I suppose it depends on how 'regular' your shape is. For polygons I suppose it's pretty good since you can pack it tightly into a circle :dontknow:

Reply 8732

Saracen's Fez

I've just rediscovered the free copy of The Sims 2 Ultimate Collection that I downloaded last year. Revision may be taking a bit of a break.

Reply 8733

Red Fox

Original post by Bude8

What do you make of this question?

Wasn't sure on how to do part b

Well, I suppose it depends on how 'regular' your shape is. For polygons I suppose it's pretty good since you can pack it tightly into a circle :dontknow:

sin(B+C)=0.5
This means B+C=either 30 or 150
Which means either A=150 or A=30
If A=150, B+C=30 which means sinB<0.5 (since both B and C must be less than 30)

3sinB + 4cosC = 6
If sinB<0.5 then 4cosC must be greater than 4.5, which is impossible obviously hence angle CAB must be 30. That's the best reasoning I could think of.

(edited 9 years ago)

Reply 8734

MangoFreak

Original post by Bude8

Well, I suppose it depends on how 'regular' your shape is. For polygons I suppose it's pretty good since you can pack it tightly into a circle :dontknow:

What would get you the mark in that question though?