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# C2 Unusual Questions watch

1. Am I missing something in Q1?

Spoiler:
Show
tan(a) = -4.705
tan-1(-4.705) = a
a = -78, so + 180 to give 102o

180-a = b+y
b+y = 78o

tan(b-y) =0.404
tan-1(0.404) = b-y

b-y = 22o

Simultaneous equations:

b+y=78
b-y=22

2b = 100
b=50
y=28

a+b+y = 50+28+102 = 180

job done

Not sure why that's part of the C2 spec but doesn't use anything you haven't learned at GCSE, it's hardly difficult
2. (Original post by TeeEm)
these are from an actual UK 2014 exam!!!

the second question I have made harder by removing one structured part.
(LOOK AT THE AMENDED FILE in post 1)
In question 2, I imagine the first part is there simply to stop people form using Heron's formula.
3. (Original post by Gaiaphage)
Am I missing something in Q1?

Spoiler:
Show
tan(a) = -4.705
tan-1(-4.705) = a
a = -78, so + 180 to give 102o

180-a = b+y
b+y = 78o

tan(b-y) =0.404
tan-1(0.404) = b-y

b-y = 22o

Simultaneous equations:

b+y=78
b-y=22

2b = 100
b=50
y=28

a+b+y = 50+28+112 = 180

job done

Not sure why that's part of the C2 spec but doesn't use anything you haven't learned at GCSE, it's hardly difficult
I hope you have not upset some, hard working but not as able as you, student users of this site ...
4. (Original post by brittanna)
In question 2, I imagine the first part is there simply to stop people form using Heron's formula.
you can still use heron's formula but it is the first part which is very interesting!
5. Well I have done question 1 (I think) so now for question 2!
6. (Original post by TeeEm)
I hope you have not upset some, hard working but not as able as you, student users of this site ...
But surely a GCSE student would have been taught everything required for that question? I guess they might not know to add 180 to the first angle but you can work that out from seeing tan(0) = tan(180)...
7. (Original post by TeeEm)
you can still use heron's formula but it is the first part which is very interesting!
Using the cosine rule twice? If I were writing an exam (especially a C2 exam), I'd feel slightly uneasy placing so many marks (I'm guessing this question was worth quite a few marks) on what is essentially a (albeit more challenging) GCSE question.
8. (Original post by Gaiaphage)
But surely a GCSE student would have been taught everything required for that question? I guess they might not know to add 180 to the first angle but you can work that out from seeing tan(0) = tan(180)...
I am glad you can see it so easy but
... my teaching experience tells me
most people (~95%) would be totally destroyed by Q1
almost everybody (~99%+) would be totally destroyed by Q2

And I mean a AS student, not an undergrad ... or a teacher/lecturer
9. (Original post by TeeEm)
I am glad you can see it so easy but
... my teaching experience tells me
most people (~95%) would be totally destroyed by Q1
almost everybody (~99%+) would be totally destroyed by Q2

And I mean a AS student, not an undergrad ... or a teacher/lecturer
Happy to take your word for it, I go to a public school so it's hardly representative. Not sure if there are some typos in Q2 but it looks like you've put |AB| three times and given two different lengths for it
10. (Original post by TeeEm)
I am glad you can see it so easy but
... my teaching experience tells me
most people (~95%) would be totally destroyed by Q1
almost everybody (~99%+) would be totally destroyed by Q2

And I mean a AS student, not an undergrad ... or a teacher/lecturer
TeeEm do you have the answers for Q1? I think I have them but I would like to check.

Question 2 I am not willing to spend energy on to be honest lol xD
11. (Original post by brittanna)
Using the cosine rule twice? If I were writing an exam (especially a C2 exam), I'd feel slightly uneasy placing so many marks (I'm guessing this question was worth quite a few marks) on what is essentially a (albeit more challenging) GCSE question.

I am sitting on a fence but many students here might find this comment contemptuous.
12. (Original post by Don Pedro K.)
TeeEm do you have the answers for Q1? I think I have them but I would like to check.

Question 2 I am not willing to spend energy on to be honest lol xD
I think Gaiaphage has put a full solution out there.
13. (Original post by TeeEm)
I think Gaiaphage has put a full solution out there.
Ah I see! Well, I got the correct answers! Although Gaiaphage has made a mistake in his final bit of working! (He gave the value of alpha as 112° rather than 102°).
14. (Original post by Gaiaphage)
Happy to take your word for it, I go to a public school so it's hardly representative. Not sure if there are some typos in Q2 but it looks like you've put |AB| three times and given two different lengths for it
thanks for letting me know about the typos...
hopefully they are obvious/I typed it in a hurry.
15. (Original post by brittanna)
Using the cosine rule twice? If I were writing an exam (especially a C2 exam), I'd feel slightly uneasy placing so many marks (I'm guessing this question was worth quite a few marks) on what is essentially a (albeit more challenging) GCSE question.

Yeah cosine rule would do it, like Q1 a GCSE student would have all the required knowledge, just perhaps not the initiative.
16. (Original post by TeeEm)
thanks for letting me know about the typos...
hopefully they are obvious/I typed it in a hurry.
No problem, the diagram was very clear so it's obvious what you meant.
17. (Original post by TeeEm)
I am sitting on a fence but many students here might find this comment contemptuous.
Maybe 'a GCSE question' wasn't the best way of phrasing it. I just meant a question that doesn't use any additional knowledge outside of that which was taught at GCSE.

I'm still not convinced it's as difficult as you think it is though. Yes, it does require two steps (using the cosine rule twice) which perhaps requires slightly more initiative. But there're only so many different things you can do with the information you've been given, and so having eliminated a few of the possibilities, I'd imagine fairly able students should be able to get to the answer without that much difficulty. Although, I guess this is the kind of question that would become a lot more difficult under exam conditions.
18. (Original post by brittanna)
Maybe 'a GCSE question' wasn't the best way of phrasing it. I just meant a question that doesn't use any additional knowledge outside of that which was taught at GCSE.

I'm still not convinced it's as difficult as you think it is though. Yes, it does require two steps (using the cosine rule twice) which perhaps requires slightly more initiative. But there're only so many different things you can do with the information you've been given, and so having eliminated a few of the possibilities, I'd imagine fairly able students should be able to get to the answer without that much difficulty. Although, I guess this is the kind of question that would become a lot more difficult under exam conditions.
It is all good ... Clearly we share slightly different learning and teaching experiences.
19. (Original post by TeeEm)
It is all good ... Clearly we share slightly different learning and teaching experiences.
Admittedly, I don't have any teaching experience and so I'm less able to judge how people would find this question.

Just out of interest, what is it in particular that students would find difficult? Is it just having a general idea of what to do? i.e. Would they not think to use the cosine rule, or not know what to do with the cosine rule (i.e. which value to calculate)? Or is it the fact that they'd use the cosine rule once, and then assume that they wouldn't have to use it again? Or is it something else?
20. (Original post by Don Pedro K.)
Ah I see! Well, I got the correct answers! Although Gaiaphage has made a mistake in his final bit of working! (He gave the value of alpha as 112° rather than 102°).
Just a typo, as you can see I put 102° when I calculated it at the start and using 112 gives 190° instead of 180° :P

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