OCR MEI C4 - June 13th 2011

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oh i got the point as (root3, -0.5) and the gradient as -root3 and put it into (y - y1) = m (x-x1) ? :/
so i got y + 0.5 = -root3(x-root3)
y + 0.5 = -root3x+3
y=-root3x+2.5

am i wrong?

Sorry what is this? Did we have to make an equation from our values, I don't remember this

Reply 581

crapmyster

Solve the equation cosec^2theta = 1 + 2cottheta

by using the identity cosec^2 = 1 + cot^2theta

You then sub this into the equation you are meant to solve then you rearrange it as normal.

I got,

cot theta = 0 ( which would give no values at all ) and

cot theta = 2 ( which would give you the values, 26.6 and 153.4 )

Reply 582

tooosh

I remember in a past paper where tan(theta) = 1/0 and the marks scheme did indeed show solutions for it, one was 90, can't remember the rest cos I don't remember the range. But they definitely expected 4 solutions for that trig question in this paper. Which I didn't get cos I cancelled cot(theta) after making sure I didn't in every past paper >.>

Reply 583

Wezzler

quick question do mei, give carry through marks.

Reply 584

SarahJayneJonas

Original post by elyn0601

i think they ask u to use x to represent y..so need to cancel all the theta..

Yeah i did it all the right way i think i just used the original equations x=2sin(-) and y=3cos2(-) rather than y=cos2(-)

so my gradient came out to be -6sin(-) giving -3root3 for pi/3 (so 3times more than it should have been)

and my cartesian equation was y=3-3/2x^2 (again 3 times bigger)

Do you think i will still get all the working marks for this? I mean all i did wrong was copying the y equation :frown:

Hopefully they will actually notice and i'll only lose a mark or something :/

(-) is meant to be theta by the way

Reply 585

Dirty Diana

Original post by Birkatron

Y = 3-0.5x^2

how did you get that?
i got y=1-(x/2)^2?!

Reply 586

Reminisce

Original post by Dirty Diana

how did you get that?
i got y=1-(x/2)^2?!

That's right.

Reply 587

zebra12345

I really screwed up C4, I think overall I have got 52/90. Will this be a D or an E?

Last year I got 95/100 in C2, 97/100 in C1, and 88/100 in S1.

What do I need in C3 and S2 for an A minimum? Is an A* even possible now? Thanks

Reply 588

Oh my Ms. Coffey

This is what I did I think.

As you can see the roots go from -2.6 rad to 0.4 rad skipping out both -90 and 90 degrees.

Im sure I also checked it using the tan quadratic equation also.

Reply 589

Ideal.

Can anyone please post how many marks were given per question in section A? That would REALLY help me!

Reply 590

Teva

Original post by bear54

Sorry what is this? Did we have to make an equation from our values, I don't remember this

writing y in terms of x. dont worry, im certain im wrong.. end of qu 4 i think

Reply 591

Ben77mc

Original post by cor898

1) 1234
2) 2345
3) 3456
4) 4567
5) 5678
6) 6789
7) 9876
8) 8765
9) 7654
10) 6543
11) 5432
12) 4321
13) 3210 Does this one count as consecutive?

fml

Reply 592

Reminisce

On the question verifying the cartesian equation and finding d. Did you guys simply substitute each point a, b and c into the equation to prove that it indeed satisfies the equation? (I don't think verify questions would require you to find the vector equation then the cartesian equation, etc.)