Edexcel C3/C4 extra things to just "know"

Anyone know the extra bits and pieces (equations, formulae etc) we need to know for C3 (and C4).

So, for example, we are expected to know the area of a sphere and cone incase it comes up in a question.

Anything else?/can anyone direct me to another link from the website. Haven't yet been able to locate anything to answer my question.

(edited 11 years ago)

Reply 1

joostan

13

Original post by lou_100

Anyone know the extra bits and pieces (equations, formulae etc) we need to know for C3 (and C4).

So, for example, we are expected to know the area of a sphere and cone incase it comes up in a question.

Anything else?/can anyone direct me to another link from the website. Haven't yet been able to locate anything to answer my question.

Good to know:

\cos(x) = cos(-x) \mathrm{ \ and} \sin(-x) = -\sin(x)

Reply 2

gaffer dean

Original post by lou_100

Anyone know the extra bits and pieces (equations, formulae etc) we need to know for C3 (and C4).

So, for example, we are expected to know the area of a sphere and cone incase it comes up in a question.

Anything else?/can anyone direct me to another link from the website. Haven't yet been able to locate anything to answer my question.

this diagram helps to remember the differential and integral of sinx, cosx, -sinx and -cosx (useful for both C3 and C4).
Identities (used when integrating C4):

sin^2x=\frac{-1}{2}(cos2x-1)

,

cos^2x= \frac{1}{2}(cos2x+1)

,

cos4x=2cos^22x-1

and also

cos4x = 1-2sin^22x

and you also need to know how the double angle formulae is derived from addition formulae and

sin^2 +cos^2=1

(C3).

(edited 11 years ago)

Reply 3

RoyalBlue7

19

How to sketch y=ln(4-2x)

Asymptote is when 4-2x=0
Crosses the x axis when 4-2x=1

And another thing:
If you want to draw inverse function graphs
1. Draw two lines as axes without labelling.
2. Sketch the graph of the function to be inversed using a pencil.
3. Make the east axis face your north.
4. Label the axes. Vertical is y horizontal is x
5. Reflect over the y axis
6. There's your inverse graphs

Practice this method with a few exampled. Like y=e^x to y=lnx, y=sinx to y=arcsinx

* I discovered this method for myself. Might not be reliable. :biggrin:

Posted from TSR Mobile

Reply 4

lou_100

OP

15

Thanks both of you, I'll write them down in my revision notes.
However, they seem to refer to shortcuts that "help" answering questions, not necessarily equations you have to know otherwise you can't even begin to answer the question (like the area of sphere/cone).

It was more that kind of thing I was searching for.

Reply 5

joostan

13

Original post by lou_100

Thanks both of you, I'll write them down in my revision notes.
However, they seem to refer to shortcuts that "help" answering questions, not necessarily equations you have to know otherwise you can't even begin to answer the question (like the area of sphere/cone).

It was more that kind of thing I was searching for.

I'm fairly confident these things don't come up in C3/4 :smile:

Reply 6

Kvothe the Arcane

20

Original post by joostan

I'm fairly confident these things don't come up in C3/4 :smile:

The area and volume equations come up in terms of connected rates of change...

Reply 7

gaffer dean

Original post by lou_100

Thanks both of you, I'll write them down in my revision notes.
However, they seem to refer to shortcuts that "help" answering questions, not necessarily equations you have to know otherwise you can't even begin to answer the question (like the area of sphere/cone).

It was more that kind of thing I was searching for.

I'm not sure about C3 but for C4 it is useful to know area and volume of sphere, cone, cube, cuboid and cylinder.

Reply 8

joostan

13

Original post by reubenkinara

The area and volume equations come up in terms of connected rates of change...

I've seen one where the volume was in a differential equation but never one where you've needed to recall that volume of a cylinder =

\pi r^2 h

or anything like that . . . But just for general maths it's nice to know these things :smile:

Reply 9

Kvothe the Arcane

20

Original post by joostan

I've seen one where the volume was in a differential equation but never one where you've needed to recall that volume of a cylinder =

\pi r^2 h

or anything like that . . . But just for general maths it's nice to know these things :smile:

Ah. Perhaps we've seen different questions.
I've regularly seen questions where it says that the the height is expanding at

Unparseable latex formula:

xhms^-^1

and it asks to find

\dfrac{dV}{dt}\ or \ \dfrac{dA}{dt}

Reply 10

joostan

13

Original post by reubenkinara

Ah. Perhaps we've seen different questions.
I've regularly seen questions where it says that the the height is expanding at

Unparseable latex formula:

xhms^-^1

and it asks to find

\dfrac{dV}{dt}\ or \ \dfrac{dA}{dt}

Hm, it doesn't really matter either way it's nice to know :smile:

Edexcel C3/C4 extra things to just "know"

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