Edexcel Maths "Proofs"

When the question asks you to prove that something is something.

Which proofs should we know?

This is pretty urgent so any help would be much appreciated!

Reply 1

Russ68993

For proof of similar triangles you need SSS, SAS, RHS, ASA
Circle theorems: Angle at circumference is twice angle at centre.
Vectors: "Prove that PQ is parallel to MR or something like that"
Algebra: "Prove that equation 1 = Equation 2" work through the Left Hand Side one and expand, solve etc, then do the same to the Right and factorise etc. to see how they are the same.
Remember, its worth a go, with the vector and algebra ones they look for marks in working, so write something!!

Reply 2

Bullit

it generally wants you to show the working out to see how you get to the answer (assuming your talking about something like a quadratic) It is hard to say with an example of the question

Reply 3

written on my heart

oh questions like: prove 1/4 = 0.25

HAHA thats a very simple version though,

Reply 4

Russ68993

written on my heart

oh questions like: prove 1/4 = 0.25

HAHA thats a very simple version though,

I am assuming people are doing Higher! :biggrin:

Reply 5

written on my heart

Russ68993

I am assuming people are doing Higher! :biggrin:

trust me i have no idea how to solve crap like that. and im doing higher too.

Reply 6

Russ68993

written on my heart

trust me i have no idea how to solve crap like that. and im doing higher too.

Higher is fine!! and proofs are ok for circle theorems which you need to know to find the angle anyway, and for congruent triangles, its for vectors and equations when they become difficult, but write something that shows you try to do something with them, eg multiplying brackets on an algebra question will get you a mark, so dont leave it blank. Same for putting units on an answer, if you havent got a clue of the answer, just write the units and you get a mark

Reply 7

SMckenna93

im doing higher
i hate maths and am ******** myself :frown:

Reply 8

garyisstuck

Russ68993

For proof of similar triangles you need SSS, SAS, RHS, ASA
Vectors: "Prove that PQ is parallel to MR or something like that"

How exactly do you do these?

Reply 9

Acta Non Verba

garyisstuck

How exactly do you do these?

Vectors is fairly simple:

I don't understand the logic behind it, but if a vector is a multiple of another vector then they are parrallel.

For instance, A6 and A2 would be parrallel.

EDIT: better example:

XY = A+B
CB = -0.5A+0.5B

These two vectors are parrallel because they're multiples of each other.

Reply 10

Russ68993

Congruent triangles: they give you 2 triangles and ask you to prove that they are the same, and you just look and think:
Are all sides the same? If yes its SSS (SIDE SIDE SIDE)
Are 2 sides and the included angle the same? then its SAS (SIDE ANGLE SIDE)
Is there a right angle, and are the hypotenuse and 1 side the same? RHS (RIGHT ANGLE, HYPOTENUSE, SIDE)
Are 2 angles and 1 side the same? SAS (SIDE ANGLE SIDE)

and for the vectors, you have to say things like, (if one length is 2a, and the other is 5a, they are parallel because they both have a)
Does that help?

Reply 11

garyisstuck

Russ68993

thanks! just one thing, why are they parallel if they both have a?

Reply 12

tsr4life

a good way to remember congruent triangles is the only set you can't have is : ASS :p:

Reply 13

Russ68993

garyisstuck

thanks! just one thing, why are they parallel if they both have a?

Because in the diagram a will always be going in one way, so that you can work it out, so if they are both a then they will be going in the same direction

Reply 14

OnDaRunFromPoor

garyisstuck

When the question asks you to prove that something is something.

Which proofs should we know?

This is pretty urgent so any help would be much appreciated!

Assuming you're talking about Circle Theorems,

There are SEVEN theorems, each with it's own proof.....so ideally we will be looking to memorise the seven theorems along with how to give reasons for the steps you take (Proofs)

Hope I havent lost ya, which I'm guessing I have!

Tbh I havent studied them all in depth.....leave that to the die-hard A* hunters....

GCSE Maths is a joke considering all the topics we should learn, the amount of hours I've personally invested, only for me to probably scrape with a C.Joke.

Reply 15

BJack

Acta Non Verba

XY = A+B
CB = -0.5A+0.5B

These two vectors are parrallel because they're multiples of each other.

But they're not. >_>

Reply 16

Unknown-User

Acta Non Verba

They're not parallel.

Reply 17

wizz_kid

garyisstuck

When the question asks you to prove that something is something.

Which proofs should we know?

This is pretty urgent so any help would be much appreciated!