[127arin]

(Original post by Z REFAN Z)
Can anyone explain to me how to do the question from June 2008 7.c.
The part im stuck on is how they get integral of cos(theta) divided by cos(theta) squared to the power of 3/2 to sec squared theta... :/

yeah man umm..they get the cos theta on top because its the differential of sin theta..so it basically like integration by substitution..and they get cos theta squared on the bottom because u use the identity sin^2 + cos^2 =1.

[Z REFAN Z]

(Original post by 127arin)
yeah man umm..they get the cos theta on top because its the differential of sin theta..so it basically like integration by substitution..and they get cos theta squared on the bottom because u use the identity sin^2 + cos^2 =1.

I knew how to do that part it was the part after i didn't understand but someone on forum explained to me

(Original post by Iepnauy)
Because on the bottom, Cos^2(theta) becomes Cos^3(theta). Square root it first, then raise it to the power of 3.

That cancels with the top bit so you're left with 1/Cos^2(theta). Which is the same as Sec^2(theta)

Thanks alot

[kingkongjaffa]

Chief examiner who did a lecture at my college said it's going to be very hard like the january one.

[Iepnauy]

(Original post by kingkongjaffa)
Chief examiner who did a lecture at my college said it's going to be very hard like the january one.

Sound good
I prefer harder papers because grade boundaries are lower so people can afford to make silly mistakes =D

[lee_vassallo]

Anyone else going slightly crazy from all this revision for one exam?

[127arin]

(Original post by lee_vassallo)
Anyone else going slightly crazy from all this revision for one exam?

Yess! too much man

[chocolatechips]

Does anyone have the January 2012 paper?

[lee_vassallo]

(Original post by chocolatechips)
Does anyone have the January 2012 paper?

[chocolatechips]

(Original post by lee_vassallo)

Thank you!

[In One Ear]

(Original post by Iepnauy)
Sound good
I prefer harder papers because grade boundaries are lower so people can afford to make silly mistakes =D

+1. The value of this is even more apparent in fp2 that we are sitting. Just did june 2010 and its a decently tough paper with many solid questions and the boundary for an A* was 70/75!!!! Get just part of the end question wrong/all right with a few minor slips and u don't get the A*. If that level of difficulty had been in a core maths exam we would have seen A* boundaries at 50/75 probably and that was easy for a fp2 exam.

[Stuffcopier]

(Original post by lee_vassallo)
Anyone else going slightly crazy from all this revision for one exam?

I woke up mumbling something about integration of 1/x to my alarm clock. Literally *going crazy*


This was posted from The Student Room's iPhone/iPad App

[GY11]

working out sinx = -1/4 .. answer in radians ..work out the value of x.. i got -0.15 which is correct but how would you get the other value? can anyone help?
its from jan 07 paper q5b.

[lee_vassallo]

(Original post by GY11)
working out inverse sin of -1/4 .. answer in radians .. i got -0.15 which is correct but how would you get the other value? can anyone help?

First rule: Draw sin graph always! It helps so much.

-0.15 is your principal value, it helps if you take the ABS value of this using your calculator to make life easier so you get +0.15.

From your graph it will be clear that there are 2 solutions: (pi + 0.15) and (2pi - 0.15) These are the solutions that fit the range 0<x<2pi

[GY11]

(Original post by lee_vassallo)
First rule: Draw sin graph always! It helps so much.

-0.15 is your principal value, it helps if you take the ABS value of this using your calculator to make life easier so you get +0.15.

From your graph it will be clear that there are 2 solutions: (pi + 0.15) and (2pi - 0.15) These are the solutions that fit the range 0<x<2pi

Thank you, but what would you do when the range is -pi<x<pi ?

[Raj K]

(Original post by kingkongjaffa)
Chief examiner who did a lecture at my college said it's going to be very hard like the january one.

ahhhh i will not sleep tonight.

[The_Jatt_Joker]

i really am scared for this paper. i think i might have to stay up late. i wish it was an afternoon so atleast wed get a few extra hours of rev

[lee_vassallo]

(Original post by GY11)
Thank you, but what would you do when the range is -pi<x<pi ?

Yeah sorry having just done the question it appears I may have misinterpreted your question. I'll show you my working:

sinx= 2/3
x=sin^-1(2/3)
x = 0.730, (pi-0.730)

sinx = -1/4
x =sin^-1(-1/4)
x = -0.253, (-pi+0.253)

The next bit is to add 0.1 to each and you finish up with 0.83, 2.51, -0.15, -2.79

[GY11]

(Original post by lee_vassallo)
Yeah sorry having just done the question it appears I may have misinterpreted your question. I'll show you my working:

sinx= 2/3
x=sin^-1(2/3)
x = 0.730, (pi-0.730)

sinx = -1/4
x =sin^-1(-1/4)
x = -0.253, (-pi+0.253)

The next bit is to add 0.1 to each and you finish up with 0.83, 2.51, -0.15, -2.79

GREAT! Thank you!!! Good luck in your exam 2morrow!.

[greenfro]

Its my birthday 2morrow, and as a present... i have a C3 exam ... WOOOO :/ haha! Good luck everyone!

[OllyHV]

Thought the Jan 2012 paper was ridiculously hard when I first sat it, I failed it btw.

Now i'm going through it, it's not that bad, I realised I made a silly mistake differentiating 1 ---> 1 instead of 0, and the 7 marker's are fairly straight forward too.