C3 OCR Jan 2013 Preparation Thread!!
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Original post by Genesis2703
Sadly you made a fatal error, it is 4/3 tan(150) not 4tan(150)
if tan6X = k, then 6X = tan^-1(k), how would the graph tan6X look, and work from there
if you look back to part i) you should notice that the theta in part i) is the 150 degrees in part ii) and the 149 and 151 are the angle alpha which is 1 degree (notice the original equation has angles X, X+A and X-A which correspond to 150, 151 and 149 respectively
if tan6X = k, then 6X = tan^-1(k), how would the graph tan6X look, and work from there
if you look back to part i) you should notice that the theta in part i) is the 150 degrees in part ii) and the 149 and 151 are the angle alpha which is 1 degree (notice the original equation has angles X, X+A and X-A which correspond to 150, 151 and 149 respectively
**** sorry my brain doesnt function at night
jesus!!! yeah i got it now! but where did the 30 come from? i thought the answer would just be tan^-1(k)/6 ?
im looking at 9ii) now ill edit this in a sec
EDIT
what do you do from here? typing it into my calculator one part gave me a surd...the other two are decimal?
(edited 11 years ago)
Original post by a10
**** sorry my brain doesnt function at night jesus!!!
yeah i got it now! but where did the 30 come from? i thought the answer would just be tan^-1(k)/6 ?
im looking at 9ii) now ill edit this in a sec
EDIT
what do you do from here? typing it into my calculator one part gave me a surd...the other two are decimal?
jesus!!! yeah i got it now! but where did the 30 come from? i thought the answer would just be tan^-1(k)/6 ?
im looking at 9ii) now ill edit this in a sec
EDIT
what do you do from here? typing it into my calculator one part gave me a surd...the other two are decimal?
When you solve trig equations there are multiple angles that are true right? I am sure you remember from C2 (and now still) that you can have multiple answers due to the period of the graph. That is where the +30 comes from, but why? I am sure you can figure it out
Oh and you misunderstood what I meant by the tan for part ii). Look at what the giant fraction equals in part i) tanX alone. So now that you've taken the 4/3's out of part ii) what must the inside equal?
Original post by a10
yeah i got it now! but where did the 30 come from? i thought the answer would just be tan^-1(k)/6 ?
yeah i got it now! but where did the 30 come from? i thought the answer would just be tan^-1(k)/6 ?
There are two solutions from 0 to 60 degrees, as the graph is tan6x so it has been stretched by 1/6.
If you draw a graph for this, it would probably explain it better than I can
. If you have a graphic calculator it's excellent for checking this sort of thing (remember that k is positive)Original post by Genesis2703
When you solve trig equations there are multiple angles that are true right? I am sure you remember from C2 (and now still) that you can have multiple answers due to the period of the graph. That is where the +30 comes from, but why? I am sure you can figure it out
Oh and you misunderstood what I meant by the tan for part ii). Look at what the giant fraction equals in part i) tanX alone. So now that you've taken the 4/3's out of part ii) what must the inside equal?
Oh and you misunderstood what I meant by the tan for part ii). Look at what the giant fraction equals in part i) tanX alone. So now that you've taken the 4/3's out of part ii) what must the inside equal?
explain part ii) caz im stuck on that bit i made it equal to my only struggle is what to do with the extra parts that are included tan149 ,tan151 and tan 150
(edited 11 years ago)
Original post by Kurak
There are two solutions from 0 to 60 degrees, as the graph is tan6x so it has been stretched by 1/6.
If you draw a graph for this, it would probably explain it better than I can. If you have a graphic calculator it's excellent for checking this sort of thing (remember that k is positive)
If you draw a graph for this, it would probably explain it better than I can
. If you have a graphic calculator it's excellent for checking this sort of thing (remember that k is positive)This completely, I didnt want to give it away completely haha
Original post by a10
explain part ii) caz im stuck on that bit i made it equal to my only struggle is what to do with the extra parts that are included tan149 ,tan151 and tan 150
Hmmm I need to think of another way to explain it, with the 4/3's out of the equation the leftovers resemble part a), just the angles are actual numbers this time. The leftovers you have = tan(something) because you proved that in part i). Look at the angle the tan has you proved in part i) and find an angle in the fraction that is the same (i.e. find what theta is via inspection)
I really dont want to just give you the answer, you wont learn anything that way
Original post by Genesis2703
This completely, I didnt want to give it away completely haha
Hmmm I need to think of another way to explain it, with the 4/3's out of the equation the leftovers resemble part a), just the angles are actual numbers this time. The leftovers you have = tan(something) because you proved that in part i). Look at the angle the tan has you proved in part i) and find an angle in the fraction that is the same (i.e. find what theta is via inspection)
I really dont want to just give you the answer, you wont learn anything that way
Hmmm I need to think of another way to explain it, with the 4/3's out of the equation the leftovers resemble part a), just the angles are actual numbers this time. The leftovers you have = tan(something) because you proved that in part i). Look at the angle the tan has you proved in part i) and find an angle in the fraction that is the same (i.e. find what theta is via inspection)
I really dont want to just give you the answer, you wont learn anything that way
right so we are using different parts here im trying to solve it using
4/3 (tan149 + tan150 + tan151) = tan theta
meaning i still have the 4/3 so solving it the way i did first time:
4/3 (sin149 + 3 sin150 + sin151) / (cos 149 + 3cos150 + cos151)
which as i thought first time resembles the first part of the question then
i can see the second part has replaced alpha and theta with angles and we know that is equal to tan theta so
?
(edited 11 years ago)
Original post by a10
right so we are using different parts here im trying to solve it using
4/3 (tan149 + tan150 + tan151) = tan theta
meaning i still have the 4/3 so solving it the way i did first time:
4/3 (sin149 + 3 sin150 + sin151) / (cos 149 + 3cos150 + cos151)
which as i thought first time resembles the first part of the question then
i can see the second part has replaced alpha and theta with angles and we know that is equal to tan theta so
?
4/3 (tan149 + tan150 + tan151) = tan theta
meaning i still have the 4/3 so solving it the way i did first time:
4/3 (sin149 + 3 sin150 + sin151) / (cos 149 + 3cos150 + cos151)
which as i thought first time resembles the first part of the question then
i can see the second part has replaced alpha and theta with angles and we know that is equal to tan theta so
?
You can't divide each sin and cos in the fraction by the corresponding cos on the bottom, that doesnt work, it would be like saying 1/3 + 1/3 + 1/3 = 1/(3+3+3) .
you are right about the 4/3tanX though, but what is X? Can't you see the form of part one corresponds to part 2? In part i) you had X-A, X and X+A as angles, and in this question you have 149,150 and 151. I can't really make it any simpler than that. what is X then???
Original post by Genesis2703
You can't divide each sin and cos in the fraction by the corresponding cos on the bottom, that doesnt work, it would be like saying 1/3 + 1/3 + 1/3 = 1/(3+3+3) .
you are right about the 4/3tanX though, but what is X? Can't you see the form of part one corresponds to part 2? In part i) you had X-A, X and X+A as angles, and in this question you have 149,150 and 151. I can't really make it any simpler than that. what is X then???
you are right about the 4/3tanX though, but what is X? Can't you see the form of part one corresponds to part 2? In part i) you had X-A, X and X+A as angles, and in this question you have 149,150 and 151. I can't really make it any simpler than that. what is X then???
yeah thats what i did first time (i mean solve it the way i did now) but i probably misunderstood what you were asking from me and ended up doing it another way which was wrong
but i got it now...i can see what your saying but why do we assume its x = 150 isn't it kinda like saying +1, -1, 0 and the +1 - 1 cancel out leaving u with 0? well not the best example but u kinda get what im implying?
i get it now tho the answer is
4/3tan150 = -4 root 3 /9
(edited 11 years ago)
Original post by a10
yeah thats what i did first time (i mean solve it the way i did now) but i probably misunderstood what you were asking from me and ended up doing it another way which was wrong but i got it now...
i can see what your saying but why do we assume its x = 150 isn't it kinda like saying +1, -1, 0 and the +1 - 1 cancel out leaving u with 0?
i get it now tho the answer is
4/3tan150 = -4 root 3 /9
but i got it now...i can see what your saying but why do we assume its x = 150 isn't it kinda like saying +1, -1, 0 and the +1 - 1 cancel out leaving u with 0?
i get it now tho the answer is
4/3tan150 = -4 root 3 /9
First of all I'll tell you that is correct. The reason the angle of 150 is used is simply that you can see that if sin(X-A)+3sin(X)+sin(X-A)/ etc. = tanX
You can see by the question in part ii) that the corresponding angle of X has to be 150, as you have sin(149)+sin(150)+sin(151), it is just something you are meant to see by intuition, hence it is at the end of the paper. Because many candidates seem to be unable to notice this pattern and apply it, generally on trig questions starting with a "show that" you are going to use the result in other parts.
Original post by Genesis2703
First of all I'll tell you that is correct. The reason the angle of 150 is used is simply that you can see that if sin(X-A)+3sin(X)+sin(X-A)/ etc. = tanX
You can see by the question in part ii) that the corresponding angle of X has to be 150, as you have sin(149)+sin(150)+sin(151), it is just something you are meant to see by intuition, hence it is at the end of the paper. Because many candidates seem to be unable to notice this pattern and apply it, generally on trig questions starting with a "show that" you are going to use the result in other parts.
You can see by the question in part ii) that the corresponding angle of X has to be 150, as you have sin(149)+sin(150)+sin(151), it is just something you are meant to see by intuition, hence it is at the end of the paper. Because many candidates seem to be unable to notice this pattern and apply it, generally on trig questions starting with a "show that" you are going to use the result in other parts.
Mmm i see, thanks bro
. When it comes to tan im a bit rusty on it i need to practise tan angles. That's very common with OCR papers the first parts are always used on other parts. What exam board are you? What are you applying for?Original post by a10
Mmm i see, thanks bro . When it comes to tan im a bit rusty on it i need to practise tan angles. That's very common with OCR papers the first parts are always used on other parts. What exam board are you? What are you applying for?
. When it comes to tan im a bit rusty on it i need to practise tan angles. That's very common with OCR papers the first parts are always used on other parts. What exam board are you? What are you applying for?If I wasnt doing OCR I wouldnt be posting on an OCR C3 thread haha
Im applying for maths and have offers at Bath, Durham, Sussex and York. Rejection from Cambridge though (love how durham who are infamous for waiting till january for offers give me an early offer, yet cambridge dont even want to interview me
)Worst thing is they said my maths scores were very good, but because I was 3UMS off an A in economics I got no interview :P
Original post by Genesis2703
If I wasnt doing OCR I wouldnt be posting on an OCR C3 thread haha
Im applying for maths and have offers at Bath, Durham, Sussex and York. Rejection from Cambridge though (love how durham who are infamous for waiting till january for offers give me an early offer, yet cambridge dont even want to interview me )
Worst thing is they said my maths scores were very good, but because I was 3UMS off an A in economics I got no interview :P
Im applying for maths and have offers at Bath, Durham, Sussex and York. Rejection from Cambridge though (love how durham who are infamous for waiting till january for offers give me an early offer, yet cambridge dont even want to interview me
)Worst thing is they said my maths scores were very good, but because I was 3UMS off an A in economics I got no interview :P
cambridge are just wayy too overatted so dont worry about it you'll probably have more fun somewhere else xD congrats on your offers
and wow cant believe i asked that ignore the stupid question my brain really doesnt function well @ night 
since your a mathmo i can assume your doing further maths as well?
Original post by a10
cambridge are just wayy too overatted so dont worry about it you'll probably have more fun somewhere else xD congrats on your offers and wow cant believe i asked that ignore the stupid question my brain really doesnt function well @ night
since your a mathmo i can assume your doing further maths as well?
and wow cant believe i asked that ignore the stupid question my brain really doesnt function well @ night since your a mathmo i can assume your doing further maths as well?
Oh yes indeed I am doing further maths, we did it in the AS Maths and Further Maths year 12 and A2 both of them Year 18. Instead of the A2 maths year 12, A2 Further year 13 route
I am doing M2, S2 and C3 in january due to further :s
Oh and I'm off to bed now, goodnight guys!!!!
Original post by Genesis2703
Oh yes indeed I am doing further maths, we did it in the AS Maths and Further Maths year 12 and A2 both of them Year 18. Instead of the A2 maths year 12, A2 Further year 13 route
I am doing M2, S2 and C3 in january due to further :s
Oh and I'm off to bed now, goodnight guys!!!!
I am doing M2, S2 and C3 in january due to further :s
Oh and I'm off to bed now, goodnight guys!!!!
year 18? haha
im doing AS further maths.... doing M1, C3 and D2 in january
Night bro
Original post by Genesis2703
Im applying for maths and have offers at Bath, Durham, Sussex and York. Rejection from Cambridge though (love how durham who are infamous for waiting till january for offers give me an early offer, yet cambridge dont even want to interview me )
Worst thing is they said my maths scores were very good, but because I was 3UMS off an A in economics I got no interview :P
)Worst thing is they said my maths scores were very good, but because I was 3UMS off an A in economics I got no interview :P
Hey I'm applying to Bath for maths too! Might see you there
. I seriously considered applying to Cambridge, but quite a few things put me off, such as the very high entry requirements. I applied to Warwick instead, as I loved the campus. Bath seemed nice, but I didn't like the campus nearly as much.Original post by a10
year 18? haha
im doing AS further maths.... doing M1, C3 and D2 in january
Night bro
im doing AS further maths.... doing M1, C3 and D2 in january
Night bro
>uses about to sleep as an excuse for year 18.
M1 is awesome, and by awesome I mean the exam paper in the summer was probably the easiest past paper i've ever seen xD
Original post by Kurak
Hey I'm applying to Bath for maths too! Might see you there . I seriously considered applying to Cambridge, but quite a few things put me off, such as the very high entry requirements. I applied to Warwick instead, as I loved the campus. Bath seemed nice, but I didn't like the campus nearly as much.
. I seriously considered applying to Cambridge, but quite a few things put me off, such as the very high entry requirements. I applied to Warwick instead, as I loved the campus. Bath seemed nice, but I didn't like the campus nearly as much.Warwick is one of the few unis that treats Guernsey (yep im not a mainland englishman) as a foreign country and charges us almost double the fees. This put me off a lot as well my familly arent exactly well off or anything special
Original post by Genesis2703
>uses about to sleep as an excuse for year 18.
M1 is awesome, and by awesome I mean the exam paper in the summer was probably the easiest past paper i've ever seen xD
M1 is awesome, and by awesome I mean the exam paper in the summer was probably the easiest past paper i've ever seen xD
my weakness with M1 is the graph questions especially when they dont put any values on the graph and give you all information in words. Other than that everything else seems fine tho atm im prioritising physics as its the most difficult exam out of the ones im doing and probably the most vital :L
Original post by Genesis2703
Warwick is one of the few unis that treats Guernsey (yep im not a mainland englishman) as a foreign country and charges us almost double the fees. This put me off a lot as well my familly arent exactly well off or anything special
Warwick is one of the few unis that treats Guernsey (yep im not a mainland englishman) as a foreign country and charges us almost double the fees. This put me off a lot as well my familly arent exactly well off or anything special
Really? Damn. At least you don't have to meet their offer then
.Original post by a10
my weakness with M1 is the graph questions especially when they dont put any values on the graph and give you all information in words. Other than that everything else seems fine tho atm im prioritising physics as its the most difficult exam out of the ones im doing and probably the most vital :L
I used to hate those then got over them. My main area of weakness where the super hard friction or tension questions. The last question on June 2012 iirc was a collision question where the ground was rough (so the particles slowed prior to collision). It was quite simple tbh... for a last question anyway.
I didnt do physics... like a fool
Original post by Kurak
Really? Damn. At least you don't have to meet their offer then .
.Yeah, but still it annoys me since Warrick seems quite cool... and I'm doing STEP anyway for fun.
Original post by Genesis2703
I used to hate those then got over them. My main area of weakness where the super hard friction or tension questions. The last question on June 2012 iirc was a collision question where the ground was rough (so the particles slowed prior to collision). It was quite simple tbh... for a last question anyway.
I didnt do physics... like a fool
I didnt do physics... like a fool
what resources did u use for M1 revision(besides papers)? i recommend maths247 on youtube he does all the further maths modules except decision modules.
Im going to start M1 revision possibly on sunday im hoping to get the physics and computing revision done at least in the next 2 weeks so i can start papers for them. 1st year physics was very very boring. 2nd year stuff very very interesting BUT concepts are very hard to explain and the exam is barely mathematical calculations about 80% of it is explain and apply 20% is maths proving formulas its insane haha.
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