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# AQA Further Maths FP1 June 5th 2015 watch

1. (Original post by qpqpqpqpqp)
can someone explain 7ciii for june 2014 - i got y=tan75x which is wrong but i don't understand the mark scheme?
i did cos^-1(-root3/2) = 150 = 2 theta, so theta = 75?
further down in the ms it says condone 75
2. (Original post by qpqpqpqpqp)
can someone explain 7ciii for june 2014 - i got y=tan75x which is wrong but i don't understand the mark scheme?
i did cos^-1(-root3/2) = 150 = 2 theta, so theta = 75?
(Original post by -jordan-)
I've just done the same question and got the same thing
That's because it isn't -root3/2. Your enlargement is scale factor root 12, so take out a factor of root 12 - cos2theta then equals -3/root12, etc
3. (Original post by Lau14)
That's because it isn't -root3/2. Your enlargement is scale factor root 12, so take out a factor of root 12 - cos2theta then equals -3/root12, etc
I got -3/root12, try and resolve that and you get the angle of 75 degrees.
4. (Original post by -jordan-)
I got -3/root12, try and resolve that and you get the angle of 75 degrees.
That is strange? (I did it in radians by accident earlier!)
5. (Original post by -jordan-)
I got -3/root12, try and resolve that and you get the angle of 75 degrees.
Ah no, nevermind, I see the problem - you have to look at both sin and cos and find the first common angle, which is 210 degrees - is this what the markscheme has?
6. I also got y=tan75x but the mark scheme only condones y=-tan75x?
7. (Original post by Lau14)
Ah no, nevermind, I see the problem - you have to look at both sin and cos and find the first common angle, which is 210 degrees - is this what the markscheme has?
Got it... but how do I find the common angle? Never seen a question like this before. Just assuming the angle is the same works for all the questions I've done has served me fine so far.
8. (Original post by -jordan-)
Got it... but how do I find the common angle? Never seen a question like this before. Just assuming the angle is the same works for all the questions I've done has served me fine so far.
You've gotten lucky a lot then!
The same way as when you're trying to find multiple solutions to a trig equation, but with two of them. Write both down (sinx = and cosx = ) and find new solutions using 180-initial for sin and plus/minus or 360-initial for cos until you find a matching pair
9. (Original post by Lau14)
You've gotten lucky a lot then!
The same way as when you're trying to find multiple solutions to a trig equation, but with two of them. Write both down (sinx = and cosx = ) and find new solutions using 180-initial for sin and plus/minus or 360-initial for cos until you find a matching pair
I just did this and got 150 as a pair?? Perhaps it's the signs messing me up?
I just did this and got 150 as a pair?? Perhaps it's the signs messing me up?
I swear I get a different answer every time I try and do this now! The method is to find the common angle, but I don't know what that is! (I really should look at the markscheme)
I just did this and got 150 as a pair?? Perhaps it's the signs messing me up?
Excuse my handwriting but here: https://www.dropbox.com/s/4hnt7u4988...09.38.png?dl=0 I think I got it figured out. I hadn't run into any problems like that before and I've managed to do most of the past papers...
12. (Original post by bartbarrow)
Excuse my handwriting but here: https://www.dropbox.com/s/4hnt7u4988...09.38.png?dl=0 I think I got it figured out. I hadn't run into any problems like that before and I've managed to do most of the past papers...
and so the penny drops! thank you!
13. (Original post by Lau14)
I swear I get a different answer every time I try and do this now! The method is to find the common angle, but I don't know what that is! (I really should look at the markscheme)
210 is the common angle.
So y=tan(105)x
14. In which order do you multiply matrices?

For example if i said find the matrix corresponding to the combined transformation of a reflection inthe line y ¼ x followed by a stretch parallel to the y-axis of scale factor 7.
15. (Original post by jake4198)
In which order do you multiply matrices?

For example if i said find the matrix corresponding to the combined transformation of a reflection inthe line y ¼ x followed by a stretch parallel to the y-axis of scale factor 7.
If you are trying to find a matrix with order of transformations AB, you find the matrix BA (it's the reverse)
16. (Original post by jake4198)
In which order do you multiply matrices?

For example if i said find the matrix corresponding to the combined transformation of a reflection inthe line y ¼ x followed by a stretch parallel to the y-axis of scale factor 7.
If you want to apply a transformation, say A and then you want to apply another one, say B then you multiply B by A to get the single matrix representing both.

So you would multiply the stretch by the reflection
17. I'm having a dumb moment
How do I make α^4+β^4 into the form only involving α+β αβ
18. (Original post by C0balt)
I'm having a dumb moment
How do I make α^4+β^4 into the form only involving α+β αβ
I usually find a^2+b^2, square it and then take away the bits you don't need to get a^4 + b^4 on it's own, then it's easy substitution. Seems quicker than doing binomial expansion and then factorising it.
19. (Original post by -jordan-)
I usually find a^2+b^2, square it and then take away the bits you don't need to get a^4 + b^4 on it's own, then it's easy substitution. Seems quicker than doing binomial expansion and then factorising it.
My dumb. Moment is strong and I can't even do it
wtf is wrong with me lmao
20. (Original post by -jordan-)
I usually find a^2+b^2, square it and then take away the bits you don't need to get a^4 + b^4 on it's own, then it's easy substitution. Seems quicker than doing binomial expansion and then factorising it.

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