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Edexcel FP2 Official 2016 Exam Thread - 8th June 2016

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Original post by economicss
@Zacken Please could you upload a sketch, thanks so much!


Step 1: You know the curves intersect at θ=π/12,5π/12\theta = \pi/12, 5\pi/12 - draw these half-lines.

Step 2: Find the area of the sector bounded between these two half lines and the circle. 12×a2×π6\frac{1}{2} \times a^2 \times \frac{\pi}{6}

Step 3: Find the blue shaded bits using integration of C1 from 0 to pi/12 + integration of C1 from 5pi/12 to pi/2.

Add step 2 + step 3.

image.jpg
Original post by Zacken
Step 1: You know the curves intersect at θ=π/12,5π/12\theta = \pi/12, 5\pi/12 - draw these half-lines.

Step 2: Find the area of the sector bounded between these two half lines and the circle. 12×a2×π6\frac{1}{2} \times a^2 \times \frac{\pi}{6}

Step 3: Find the blue shaded bits using integration of C1 from 0 to pi/12 + integration of C1 from 5pi/12 to pi/2.

Add step 2 + step 3.



Thank you!! Please could you explain a bit of this question to me, I got it right apart from I thought the angle for the sector of the circle would be pi/ 6 as if it's 2pi/3 plus the other area I worked out then wouldn't this be the top bit of the circle rather than the shaded bit? Or is my
Method incorrect? Thanks :smile:
Original post by economicss
image.jpg

Thank you!! Please could you explain a bit of this question to me, I got it right apart from I thought the angle for the sector of the circle would be pi/ 6 as if it's 2pi/3 plus the other area I worked out then wouldn't this be the top bit of the circle rather than the shaded bit? Or is my
Method incorrect? Thanks :smile:


@Zacken
Original post by economicss


How many of your qs has the poor guy helped you with ahaha, he's probs got work of his own to do.
Original post by BBeyond
How many of your qs has the poor guy helped you with ahaha, he's probs got work of his own to do.

Sorry haha, I got rejected from Cambridge btw if that was why you had animosity towards me 😂
Original post by economicss


Zacken's not going to be there in the exam. Try and do as much as possible yourself and use other resources such as examsolutions, mark schemes etc to get the answer, because you have to remember that even though zacken is insanely patient at some point his patience will run out if you keep spamming him with questions, so I'd suggest you try and rely on him a bit less.
Original post by economicss
Sorry haha, I got rejected from Cambridge btw if that was why you had animosity towards me 😂


What ahaha :tongue:
Original post by economicss


Thank you!! Please could you explain a bit of this question to me, I got it right apart from I thought the angle for the sector of the circle would be pi/ 6 as if it's 2pi/3 plus the other area I worked out then wouldn't this be the top bit of the circle rather than the shaded bit? Or is my
Method incorrect? Thanks :smile:


Surely the two half lines are π6\frac{\pi}{6} and 5π6\frac{5\pi}{6} so that the "top" angle between those two lines is 2π3\frac{2\pi}{3} and hence the "bottom" angle or the sector angle is 2π2π3=4π32\pi - \frac{2\pi}{3} = \frac{4\pi}{3}.

Caveat: I've barely looked at the question.
I've got a nice and short question:

If the complex number z=(1+itanθ)3\displaystyle z=\left ( 1+i\tan\theta \right )^{3},

Show that 13tan2θcos3θcos3θ\displaystyle 1-3\tan^{2}\theta \equiv \dfrac{\cos3\theta}{\cos^{3} \theta}.
Original post by aymanzayedmannan
I've got a nice and short question:

If the complex number z=(1+itanθ)3\displaystyle z=\left ( 1+i\tan\theta \right )^{3},

Show that 13tan2θcos3θcos3θ\displaystyle 1-3\tan^{2}\theta \equiv \dfrac{\cos3\theta}{\cos^{3} \theta}.


Side note, you could also just do:

Unparseable latex formula:

\displaystyle[br]\begin{equation*} 1 - \frac{3\sin^2 \theta}{\cos^2 \theta} \equiv \frac{\cos^2 \theta - 3\sin^2 \theta}{\cos^2 \theta} \equiv \frac{\cos^3 \theta - 3\cos \theta \sin^2 \theta}{\cos^3 \theta} \equiv \frac{\Re \left(\cos \theta + i\sin \theta\right)^3}{\cos^3 \theta} \equiv \frac{\cos 3\theta}{\cos^3 \theta} \end{equation*}



Edit to add: I can't immediately see how to do it the way you intended. I get that (1+itanθ)3=13tan2θ\Re(1 + i\tan \theta)^3 = 1 - 3\tan^2 \theta, but then what?
(edited 8 years ago)
Original post by Zacken
Side note, you could also just do:

Unparseable latex formula:

\displaystyle[br]\begin{equation*} 1 - \frac{3\sin^2 \theta}{\cos^2 \theta} \equiv \frac{\cos^2 \theta - 3\sin^2 \theta}{\cos^2 \theta} \equiv \frac{\cos^3 \theta - 3\cos \theta \sin^2 \theta}{\cos^3 \theta} \equiv \frac{\Re \left(\cos \theta + i\sin \theta\right)^3}{\cos^3 \theta} \equiv \frac{\cos 3\theta}{\cos^3 \theta} \end{equation*}



Edit to add: I can't immediately see how to do it the way you intended. I get that (1+itanθ)3=13tan2θ\Re(1 + i\tan \theta)^3 = 1 - 3\tan^2 \theta, but then what?


(1+itanθ)3 \displaystyle (1 + i\tan \theta)^3

(cosθcosθ+isinθcosθ)3 \displaystyle \left(\frac{\cos \theta}{\cos \theta} + i\frac{\sin \theta}{\cos \theta}\right)^3

(1cosθ)3(cosθ+isinθ)3 \displaystyle \left(\frac{1}{\cos \theta}\right)^3 \: (\cos \theta + i\sin \theta)^3

then regular de moivre theorem
Original post by DylanJ42
(1+itanθ)3 \displaystyle (1 + i\tan \theta)^3

(cosθcosθ+isinθcosθ)3 \displaystyle \left(\frac{\cos \theta}{\cos \theta} + i\frac{\sin \theta}{\cos \theta}\right)^3

(1cosθ)3(cosθ+isinθ)3 \displaystyle \left(\frac{1}{\cos \theta}\right)^3 \: (\cos \theta + i\sin \theta)^3

then regular de moivre theorem


Oh, niiice. Obvious in hindsight. :colondollar: Thanks!
ImageUploadedByStudent Room1459972510.981910.jpg
Hey everyone
Does anyone know which paper is this?or how to get its markscheme? I tried looking it up online couldn't find anything. Thanks


Posted from TSR Mobile
Original post by jkhan9625
ImageUploadedByStudent Room1459972510.981910.jpg
Hey everyone
Does anyone know which paper is this?or how to get its markscheme? I tried looking it up online couldn't find anything. Thanks


Posted from TSR Mobile


june 2013 withdrawn paper
Original post by DylanJ42
june 2013 withdrawn paper


Thanks a lot


Posted from TSR Mobile
Hi, could anyone give any advice please on sketching the graph in question 5cii of this paper https://8dedc505ac3fba908c50836f59059ccce5cd0f1e.googledrive.com/host/0B1ZiqBksUHNYdHIxUkJmdndfMlE/June%202013%20QP%20-%20FP2%20Edexcel.pdf Thanks
Original post by economicss
Hi, could anyone give any advice please on sketching the graph in question 5cii of this paper https://8dedc505ac3fba908c50836f59059ccce5cd0f1e.googledrive.com/host/0B1ZiqBksUHNYdHIxUkJmdndfMlE/June%202013%20QP%20-%20FP2%20Edexcel.pdf Thanks


Literally just done this paper. Uhm, you should know that there are minimum points at (±2,4)(\pm \sqrt{2} ,4) and that the yy-axis is an asymptote (since you have x2x^2 in the denominator) and then the graph tends to positive infinity as xx approaches infinity. Then the curve tails off the positive infinity as xx tends to positive and negative infinity. Also there is symmetry in the yy-axis because it's an even function i.e f(x)=f(x)f(-x) = f(x) since all your xx terms are squared.

Edit: also your function will always lie above your xx-axis since it is always positive due to the squared terms.
(edited 8 years ago)
Original post by Zacken
Literally just done this paper. Uhm, you should know that there are minimum points at (±2,4)(\pm \sqrt{2} ,4) and that the yy-axis is an asymptote (since you have x2x^2 in the denominator) and then the graph tends to positive infinity as xx approaches infinity. Then the curve tails off the positive infinity as xx tends to positive and negative infinity. Also there is symmetry in the yy-axis because it's an even function i.e f(x)=f(x)f(-x) = f(x) since all your xx terms are squared.

Edit: also your function will always lie above your xx-axis since it is always positive due to the squared terms.


How did you do? Thanks for that, very helpful :smile:
Original post by economicss
How did you do? Thanks for that, very helpful :smile:


I did okay, it was a nice one, I think. You? :smile:
Original post by Zacken
I did okay, it was a nice one, I think. You? :smile:


Yeah okay thanks :smile: Hoping we get a similar difficulty one this year!

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