General Thoughts: Mathematics Ext 1 (3 Viewers)

[chriss95]

For the projectile, 66.97 deg <= @ <= 75 deg. For the rates/plane, the first part could be proved using cos rule and Pythagoras, and for the second part I got something that looks like



Though I might have gotten the signs or cos/sins mixed up.

I got 180(60-cos(a)) / root(901-30cos(a)) ... don't know how you got sin(a) on the top, because you differentiate with respect to 'u', not 'a'

 

[habitres]

Fucked up big time. Got too stressed and to many stupid mistakes in the multiple choice. Probably ~50/70 if I'm lucky.
Could do all of question 6, but I ran our of time so lost 5 marks for just not being able to complete the last one.

Oh well.
Time for physics and chemistry study.

 

[deswa1]

Found the paper easier than past papers 2011, 2010 etc however for question 14 I couldn't prove that they triangles were congruent! >:O I had the hypotenuse, side but I couldn't prove the 90 degree angle in triangle MXS. Could someone help me with that?
Also had trouble with b iii, my angles didn't overlap i had angles ranging from 15<theta<23? and x>50 for the height equation. AND I couldn't do anything from part C
SO IF ANYONE COULD DO ANY OF THESE QUESTIONS PLEASE FEEL FREE TO LET ME KNOW HOW YOU DID IT

You know that one side is common, two others are equal because of equal radii and the other two are equal because diagonals in a rectangle bisect each other.

For b) iii), you need to consider that the domain of sin2(theta) is from 0<theta<180, not just 0<theta<90

 

[Nws m8]

Did you guys get n is divisible by 4 for that one on the non-zero constant term?

how'd you go m8?

 

[nucgaek]

Found the paper easier than past papers 2011, 2010 etc however for question 14 I couldn't prove that they triangles were congruent! >:O I had the hypotenuse, side but I couldn't prove the 90 degree angle in triangle MXS. Could someone help me with that?
Also had trouble with b iii, my angles didn't overlap i had angles ranging from 15<theta<23? and x>50 for the height equation. AND I couldn't do anything from part C
SO IF ANYONE COULD DO ANY OF THESE QUESTIONS PLEASE FEEL FREE TO LET ME KNOW HOW YOU DID IT

To prove they're congruent, you use the diagonals are equal and bisect so you get a 3rd and final pair of sides equal.
Don't remember 14 perfectly but b)ii) I got something around 70degrees (there was a smallish range)

 

[Sanjeet]

Did you guys get n is divisible by 4 for that one on the non-zero constant term?

That's what I wrote, but I didn't know how to express it mathematically

 

[nucgaek]

That's what I wrote, but I didn't know how to express it mathematically

"n is a multiple of 4"
It was 1 mark, if you wrote something like that you should pick up a mark

 

[Nws m8]

That's what I wrote, but I didn't know how to express it mathematically

it was 1 marker

 

[Currybear]

you change the equation into Rcos(nt-whatever) = -5
then you work it out. I got 1.5 seconds or something like that (i probably solved it wrong knowing myself)

Yes! 1.5 FTW

 

[Rafy]

Please keep discussion related to solutions and specific questions to the relevant stickied thread

......

 

[hsc2012la]

You know that one side is common, two others are equal because of equal radii and the other two are equal because diagonals in a rectangle bisect each other.

For b) iii), you need to consider that the domain of sin2(theta) is from 0<theta<180, not just 0<theta<90

OMG DAM IT, how could I have not seen the other side T_T and thanks for your help

 

[kenkap]

Any chance of taking marks off for abbreviating "simple harmonic motion" to SHM?



so you get 22.something

yeahhhh!!

 

[cartoonmaiz]

I got that too chriss95. For the last part of q11, I said that since n has to be an integer, r has be to divisible by 3. Since it was n=4r/3.

 

[HeroicPandas]

For the projectile, 66.97 deg <= @ <= 75 deg. For the rates/plane, the first part could be proved using cos rule and Pythagoras, and for the second part I got something that looks like



Though I might have gotten the signs or cos/sins mixed up.

dam, i forgot u was 30 xD

I got everything up to there in terms of u and alpha and gave up cos i didnt know what was u xD

 

[nucgaek]

I got that too chriss95. For the last part of q11, I said that since n has to be an integer, r has be to divisible by 3. Since it was n=4r/3.

The question asked on a condition for n, not r.

From all accounts the correct answer is "n is a multiple of 4"

 

[Amleops]

For a 3U exam it was easier than usual.

Hoping for somewhere in the 60s.

 

[cartoonmaiz]

nucgaek I then said that n=4,8,12... would that also be marked right?? I didn't specifically say that n was a multiple of 4...

 

[lolcakes52]

Very easy exam, looking at 68~69

 

[Nws m8]

Very easy exam, looking at 68~69

I'd say 70

 

[HeroicPandas]

LOL do u know the inverse functions question part iii.............

It says to draw f(x) and f^-1(x) and i drew y=x and y=f(x).......................epic fail