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Edexcel A-level Pure Maths 1 - 5th June 2019 [Exam Discussion]

Reply 580

unicornlover1

12

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is anyone able to help me this trig question, i don’t understand the method :smile:

))

Reply 581

ohemgee11

7

Don't worry about this. It's just fancy notation of what you already know
Basically, you know that integrating the area under the curve is like summing all the areas of really thin (rectangular) strips under the curve, right?
Well, this is what the sum means, in plain english: Sum all the areas of the strips under the curve, from x=a, to x=b (which are your limits), where the area of each strip = width x height = yx = f(x) X delta x (because y= f(x) and the 'width' of each rectangular strip is delta x, when you're integrating with respect to x)

For the integral to be as accurate as possible, the width of each strip needs to be as small as absolutely possible. This is where the limit: delta x --> 0 comes from, so now the integrand is reduced to just f(x)

Original post by Khushi.S

WHAT is that... never seen that come up anywhere

(edited 4 years ago)

Reply 582

ohemgee11

7

Here, they are using the addition (or subtraction, whatever you'd like to call it) formulae for sin(A+B) and cos (A-B)
- sin(A+B) = sinAcosB + sinBcosA
- cos(A-B) = cosAcosB + sinAsinB
These type of questions, where you have to prove identities, involve showing that the LHS (Left hand side) = RHS

So, all you have to do is:
1) Expand sin (x + pi/4), using the proper identity
2) Expand cos (x - pi/4), using the proper identity
3) Show that they are identical
(Note that in your expansions, you will have sin(pi/4) terms and cos (pi/4) terms. These can just be rewritten as sqrt (2)/2 )

Original post by unicornlover1

is anyone able to help me this trig question, i don’t understand the method :smile:

))

Reply 583

JayrZ

12

Original post by unicornlover1

Where can I find the mock? Is this just one of the specimen papers?

yh I think

Reply 584

unicornlover1

12

Original post by ohemgee11

Here, they are using the addition (or subtraction, whatever you'd like to call it) formulae for sin(A+B) and cos (A-B)
- sin(A+B) = sinAcosB + sinBcosA
- cos(A-B) = cosAcosB + sinAsinB
These type of questions, where you have to prove identities, involve showing that the LHS (Left hand side) = RHS

So, all you have to do is:
1) Expand sin (x + pi/4), using the proper identity
2) Expand cos (x - pi/4), using the proper identity
3) Show that they are identical
(Note that in your expansions, you will have sin(pi/4) terms and cos (pi/4) terms. These can just be rewritten as sqrt (2)/2 )

Original post by ohemgee11

Here, they are using the addition (or subtraction, whatever you'd like to call it) formulae for sin(A+B) and cos (A-B)
- sin(A+B) = sinAcosB + sinBcosA
- cos(A-B) = cosAcosB + sinAsinB
These type of questions, where you have to prove identities, involve showing that the LHS (Left hand side) = RHS

So, all you have to do is:
1) Expand sin (x + pi/4), using the proper identity
2) Expand cos (x - pi/4), using the proper identity
3) Show that they are identical
(Note that in your expansions, you will have sin(pi/4) terms and cos (pi/4) terms. These can just be rewritten as sqrt (2)/2 )

That makes more sense aha.
Thank you so much 😊

Reply 585

ohemgee11

7

No worries! :smile:

Original post by unicornlover1

That makes more sense aha.
Thank you so much 😊

Reply 586

VictiniCup

16

Anyone have a link to specimen papers mentioned?

Reply 587

Not_my_real

3

Does anyone know what the grade boundaries are likely to be for this exam for A and A* based on the recent mock paper?

Reply 588

Ninja1231

2

Hi, can someone please share a link of all the past papers and specimen papers that are useful, really running low on time 😅

Reply 589

msbx

10

Any general tips for how to approach proof questions? This is the one area of the spec i neglected to learn ( we never got taught it ). I have memorised the main contradiction proofs ( root two, root three and infinate primes) and i know how to write down odd and even in terms of n. Anything else i should learn generally?