Edexcel A2 C4 Mathematics June 2015 - Official Thread

Original post by 123456789012

Oh okay, I get it! Thanks a lot! :smile:

No worries :wink:

Reply 601

Original post by MyNameIsMyName

Hi.

So basically i wanted to know whether we need to know how to do part B for edexcel spec i haven't really come across those area questions apart from solomon papers.

3. Relative to a fixed origin O, the point A has position vector 3i + 2j – k, the point B has position vector 5i + j + k, and the point C has position vector 7i – j.

(b) Find the exact value of the area of triangle ABC. (3)

Asking us to calculate the area with just 3 position vectors. No lines intersection etc. Just assume the triangle as they all come from 0 so we can draw that. part A was calculate the cosine of triangle ABC pretty straight forward.
Just wanted to know whether part B is in the spec otherwise i wont bother with doing those questions wasting my time. If we need to can someone please give me a good method to do that. 1/2ABsinC etc

Yes That can come up. Since you have the cosine you can get the sine of the angle. Now you can get the distance between each point then use the formula you have quoted. Fin the lengths of the adjacent sides to the angle you worked out.

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Reply 602

Original post by physicsmaths

Og damn i forgot. Quote me later on and ill do it, just doing a past paper rn.

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Have you tried the question yet?

Reply 603

Original post by Tow

Have you tried the question yet?

Ah thanks for reminding. I'll post it in a few minutes.

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Reply 604

studentwiz

how do you show 2 lines intersect in vectors?

Reply 605

Original post by Tow

Can you guys help me with a Q?

It's practice paper A2 for C4

This is the question ImageUploadedByStudent Room1432491016.269083.jpg

I'm stuck on d) :P

I got this:
ImageUploadedByStudent Room1432491088.974389.jpg

The answer is this:
H=A^2/4
H=0.25

Can anyone explain? :P

ImageUploadedByStudent Room1432577784.828613.jpg

Reply 606

Original post by studentwiz

how do you show 2 lines intersect in vectors?

Find value of parameter such that two components are equal then sub into third one and if that is also the same then they intersect, last part is key.

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Reply 607

studentwiz

can someone explain how 5ln5/4 + 2ln4/5 = 3ln5/4

Reply 608

Original post by studentwiz

can someone explain how 5ln5/4 + 2ln4/5 = 3ln5/4

Use log laws

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Reply 609

Original post by physicsmaths

LOL

I made the most stupid mistake xD

Put wrong numbers in calculator lol

Thanks anyway

Reply 610

aersh8

Original post by studentwiz

can someone explain how 5ln5/4 + 2ln4/5 = 3ln5/4

1432579159738.jpg45.8KB

Reply 611

Original post by studentwiz

can someone explain how 5ln5/4 + 2ln4/5 = 3ln5/4

A few ways to do it

I did the most simple and easy way

ImageUploadedByStudent Room1432579134.124344.jpg

Reply 612

Original post by Tow

A few ways to do it

I did the most simple and easy way

ImageUploadedByStudent Room1432579134.124344.jpg

EDIT: did extra working out so you understand :smile:

Reply 613

Anyone got really hard/challenging questions?

I've done most of the hard edexcel past paper ones so anything else? :smile:

Reply 614

Gilo98

Original post by Tow

Anyone got really hard/challenging questions?

I did most of the hard edexcel past paper ones so anything else? :smile:

Tried solomons?

Reply 615

Original post by Gilo98

Tried solomons?

Don't really wanna do the papers because they're just so different to edexcel.

But are there any hard ones that I could try from Solomon?

Reply 616

Gilo98

Original post by Tow

Don't really wanna do the papers because they're just so different to edexcel.

But are there any hard ones that I could try from Solomon?

They also do worksheets which I think are good practice - especially for questions like that infamous trig Q on the June 2013 C3 paper. All the solomon papers are 'harder' than Edexcel ones. Might want to also take a look at the 'Gold' edexcel papers

Reply 617

studentwiz

Original post by Tow

A few ways to do it

I did the most simple and easy way

ImageUploadedByStudent Room1432579134.124344.jpg

Original post by aersh8