Edexcel FP2 Official 2016 Exam Thread - 8th June 2016

In this question why is the angle not marked as $3\pi/4$?

(apologies for rubbish quality)

I am going to be keeping you guys busy with questions as I am basically self teaching FP2 having started on Friday you have been a great help so far

Looks like an error.

In polar coordinates, when finding area if you use limits of pi and 0 then times answer by 2 and get correct answer but the markscheme says to use limits of 2pi and 0, would you lose the marks?

And he's back again



In part (e) what are the formulae used in calculating the area? I can't seem to find them in the textbook so assume they may be from one of the earlier modules and my memory isn't too great...

Please could anyone explain how to do question 19b and 19d here, really struggling with them! Thanks

I think for 19b you have to split it up into arg(z-2) - arg(z+i) = pi/4. As z represents any point, x+iy, then you know that if it lies on the negative real axis then y=0 so arg(x-2) = pi and arg(x+i) must therefore equal 3pi/4. Tan(3pi/4) = -1 so then you can work out the x coordinate from there with trig.

With 13d, for part i, I think you can use the idea that the angle subtended at the centre of the circle from any two points on the circle is double the angle subtended at the circumference of the circle. For part ii, I'm not sure if there is a circle theorem you can use but you could show the arc length of A is 3/4 the circumference by working out the radius of the circle and the angle the arc moves through.

Thanks so much, I'm probably missing the obvious but how does y=0 mean that arg (x-2)= pi please, sorry can't think of the link! Thanks

Is this another error in the solutionbank? Highlighted in red I am pretty sure the $i$ should be a $1$?



Or am I being dumb (I am prone to temporary lapses of maths ability)

As y=0, think of there being no imaginary component to the complex number. As x lies on the negative real axis, then x-2 can only be a negative real number, hence the argument of that must be pi

Correct. That is an error. However, it is rectified in the subsequent working.

HAVE I GONE MAD!?

First order differential question

Please tell me this makes no sense because it certainly makes no sense to me. They seem to have the x terms flipped for no reason and pulled some t terms out of thin air.

Could someone please check this for me to see if I still have my sanity

HAVE I GONE MAD!?

First order differential question

Please tell me this makes no sense because it certainly makes no sense to me. They seem to have the x terms flipped for no reason and pulled some t terms out of thin air.

Could someone please check this for me to see if I still have my sanity

Hmmm very strange indeed. Think I may be going mad aswell now -.-..

If I had to guess I would say that it's not suppose to be dy/dx but dx/dt. That's probably where mistake is. If it were dy/dx then that would be a really easy differential equation to solve.

Aha looks like another error to me :P

I see, thanks for your help Please could you draw a sketch for part di as I know the circle theorem you mean but I can't seem to draw it so that it helps me to find the answer! Thank you

Please could anyone explain how to do question 3c in here? Thanks