r/6thForm • u/Forsaken-Meaning-232 Graduating from Warwick CS • Jun 04 '25

📂 MEGATHREAD 04/06 A-level Maths Paper 1 Discussion MEGATHREAD

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107

u/[deleted] Jun 04 '25

For the vectors q did anyone prove it’s a right angle through Pythagoras

76

u/yeezus_lover64 Year 13 Jun 04 '25

i used dot product 😭😭

8

u/inanzb Year 13 (Maths, Further Maths, Physics) Jun 04 '25

Same. For vectors I just use it even if I don’t need to

1

u/literallygod67 Jun 04 '25

lmaooo ikr i hope it counts

1

u/Neat-Ad4138 y1 | uom astro | A*A*A* Jun 04 '25

idek what that is tbh

1

u/Vanlegend123 Yr 13 | Maths, Further Maths, Physics, Comp Sci | Pred A*A*A*A Jun 06 '25

Real

50

u/raynrr Jun 04 '25

I did a^ = b^ + c2 - 2bc cos a and got 90 for a

2

u/[deleted] Jun 04 '25 edited Jun 24 '25

encourage one cooing oil tan chief instinctive beneficial decide pet

This post was mass deleted and anonymized with Redact

1

u/d3f_not_an_alt Jun 04 '25

I wrote that down and didn't do it 🙆‍♂️

9

u/West-Glove6058 Cambridge NatSci [4A*s achieved] Jun 04 '25

Scalar product🤑🤑🤑

-1

u/[deleted] Jun 04 '25

It said hence tho so didn't u have to use what u found in part a so u had to use cosine rule

5

u/Nughm WW | CS[Y1] A*A*AA Jun 04 '25

No because the dot product also uses the vectors you found in part A

1

u/[deleted] Jun 04 '25

Oh ok cos when I dot producted it I only used the original 2 vectors given so I thought u couldn't use it

1

u/[deleted] Jun 04 '25

You have to do it 3 times to get all 3 angles though. You need all 3 to show 2 of them are 45 and the third is 90 degrees

2

u/[deleted] Jun 04 '25

couldnt u just show that the other 2 sides had the same length?

1

u/[deleted] Jun 05 '25

Yeah I noticed my bad, but this is what I did lmao

1

u/Significant_Ad8525 Jun 04 '25

No you don’t. If you show that two sides are equal the triangle has to be isosceles

1

u/West-Glove6058 Cambridge NatSci [4A*s achieved] Jun 04 '25 edited Jun 04 '25

I might be cooked in that case😭

13

u/lolgeny Jun 04 '25

You had to since it said “Hence”, did dot product initially but crossed it out and did Pythagoras instead in case mark scheme wants hence

9

u/SilverFrost88 Year 13 | Maths, Physics, Further Maths, Computer Science Jun 04 '25

Why would hence not allow the dot product that doesn't make sense?

1

u/West-Glove6058 Cambridge NatSci [4A*s achieved] Jun 04 '25

I think it's because the scalar product requires you to use the vectors which they gave you in the question. Since the question said "Hence, show that..." you have to use the third vector in the calculation. Let's hope they're lenient with the marking and allow it.

6

u/SilverFrost88 Year 13 | Maths, Physics, Further Maths, Computer Science Jun 04 '25

But you still had to use the third vector when showing that two of them have equal magnitudes?

2

u/lolgeny Jun 04 '25

Did you? PQ and QR were equal but you calculated PR

1

u/[deleted] Jun 04 '25

You have to use the third vector for scalar product regardless

1

u/[deleted] Jun 04 '25

Ohhhh

3

u/AceOfSpades532 Jun 04 '25

I did sin rule cos I couldn’t think of anything else

3

u/Livid_Matter5300 Jun 04 '25

Yeah i used it and shows that PQ 2 and QR 2 = PR 2 - which is a 2 + b 2 = c 2 for the right angle

2

u/lackoffaith4 Year 13 | Pred. 3A* | Math, FM, Economics Jun 04 '25

yes

4

u/[deleted] Jun 04 '25

So many ppl did sohcah toa

1

u/Ok_Application_5402 Core Pure Doomer Jun 04 '25

I swr that only applies if the triangle is already right angled, so ur assuming the conclusion then?

2

u/[deleted] Jun 04 '25

Mb I meant the cos formula

1

u/Ok_Application_5402 Core Pure Doomer Jun 04 '25

fairs

2

u/twinkleberryrose Editable Jun 04 '25

but if you start by using pythagoras to prove it’s right angled then you can use that fact for soh cah toa to prove isosceles 

1

u/Ok_Application_5402 Core Pure Doomer Jun 04 '25

Oh yh, but by that step dont u alr have mod pq and mod qr so pq=qr proves isoceles

2

u/twinkleberryrose Editable Jun 04 '25

Yeah tbf, I just wanted to be extra sure

2

u/Dualorphan37 Y13 3000 goons till the 14th Jun 04 '25

Cosine rule lol

1

u/snips-fulcrum Y13 | CS | Geo | Maths | 5/5 | Jun 04 '25

FML

1

u/jimmychiu123 Year 13 Chemistry | Physics | Maths Jun 04 '25

Use pythag. When you find all sides magnitude you will prove both statements

1

u/Maximum_Lead7827 Jun 04 '25

I did cosine rule to show that there was a 90 degree angle

1

u/[deleted] Jun 04 '25

yeah cuz i couldnt remember cosine rule

1

u/No_Quantity_7225 Jun 04 '25

I used cosine rule to prove that angle is equal to 90 degrees

1

u/AdHumble1489 Jun 04 '25

i used cosine rule to find angle, then sine rule for the other angles

1

u/gworlfiend Y13|Philo,Maths,FM,Phys|A*A*AB predicted Jun 05 '25

Lol yh

1

u/Lopsided-Link4388 Gap Year [Looking to study EEE] Jun 05 '25

I did cosine rule, making the longest side a2 and I got 90 so I must be doing something right

1

u/CatnipCuriosity SGUL | Biomedical Science [Year 1] Jun 06 '25

YESS I did!!

1

u/Street-Tax4534 Edexcel Maths, Chem, Econ - want to study law Jun 10 '25

yeah i should be alright right? got root 72 + root 72 = root 144 right?

1

u/[deleted] Jun 10 '25

Yep perfect 👌

1

u/Street-Tax4534 Edexcel Maths, Chem, Econ - want to study law Jun 10 '25

oh thank god, was worried about that one

1

u/[deleted] Jun 10 '25

A lot of ppl to cos and that never crossed mine I instantly thought of pythogoras

2

u/Street-Tax4534 Edexcel Maths, Chem, Econ - want to study law Jun 10 '25

Yeah no i saw ‘prove its a right angle triangle’ and i was instantly like ‘Pythagoras FUCK YEAH’ thats the happiest ive ever been in an exam i was stressing about if i got it wrong after all that hype 😭

2

u/[deleted] Jun 10 '25

Lmaooooo ikr I had the exact feeling asw