OCR MEI Maths: Paper 1, Unofficial mark scheme

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Pretty sure it was
(sinx/1-cosx)-(1/sinx) = cotx
LHS
(sin^2x-(1-cosx))/sinx(1-cosx)
((1-cos^2x)+cosx-1)/sinx(1-cosx)
(cosx-cos^2x)/sinx(1-cosx)
cosx(1-cosx)/sinx(1-cosx)
cosx/sinx = cotx RHS

Original post by mollyann2112

Do that question ask for the value of n corresponding with the maximum value of S? Because I’m pretty sure it just asked for the maximum S value as n varies. Also what was the trig proof, I thought I had it then it went weird so I had to move on :frown:

(edited 4 years ago)

Reply 81

MrMoment

I wonder what they’ll do about the error..

Reply 82

amartyasen

With the arithmetic sum question you coulf also have worked out n when the sequence becomes negative bec at that point the sum starts falling.

Reply 83

ahhmed123

Original post by Andrejcouture27

I got 0.506 for the coefficient of friction.

Same, the people that didnt get that didnt use exact values

Reply 84

hdjdjs

i got 1.6 (clearly did something wrong) for the sum of the arithmetic sequence... what were the actual values bc calculating it now gives me n=7 when n=16

Reply 85

Dr..D

Original post by C342

nah same question, I differentiated the sum formula

differentiation yeah u r right because they said maximum
I didn't even think about differentiating in the exam lol

Reply 86

danstk

How many marks was the sum question?

Reply 87

ullaelfadill

How do you know that k=-4?

Original post by MrMoment

k=-4 and 4i+9j

Reply 88

YasminLE

Do you think that the grade boundaries will be a lot lower or just a bit lower than last year felt a lot harder

(edited 4 years ago)

Reply 89

ahhmed123

People that got 0.2 ish answers didnt realise that acceleration was negative.

Original post by uffyeah$

For the series one, I got n is maximum at 15, and that summing the series to n=15 gets the sum to be 202,500. What did other people get? also, for the last question I got the coefficient of friction to be 0.221. It seems that answers are evenly split between 0.50 and 0.22

Reply 90

Osas..

I did this too originally hen realised I actually had to use 4t^2 instead of 8t because that’s they y coordinate not the x one

Original post by Isaacgresham14

Did something like this but couldn't get the equations to equal because of the 8t in PQ which wasn't in PR but I noticed when t=1 they do equal each other.

Reply 91

ahhmed123

Paper was easier than 2018. Id assume itll be similar maybe slightly lower. But theres stats and comprehension to come yet.

Original post by YasminLE

Do you think that the grade boundaries will be lower than last year felt a lot harder

Reply 92

ahhmed123

Its first year core 1 coordinate geometry, simply use formule square root of (x2-x1)^2 +(y2-y1)^2. You end up with the same equations for both lines.

Original post by Osas..

I did this too originally hen realised I actually had to use 4t^2 instead of 8t because that’s they y coordinate not the x one

Reply 93

YasminLE

I found this one so so much harder than last years

Original post by ahhmed123

Paper was easier than 2018. Id assume itll be similar maybe slightly lower. But theres stats and comprehension to come yet.

Reply 94

ahhmed123

2018 had a nasty trig one, and a few proof questions that were hard.

Original post by YasminLE

I found this one so so much harder than last years

Reply 95

flixipix

Original post by hdjdjs

i got 1.6 (clearly did something wrong) for the sum of the arithmetic sequence... what were the actual values bc calculating it now gives me n=7 when n=16