MedVision ad

2012 Year 9 &10 Mathematics Marathon (2 Viewers)

TerenceM

New Member
Joined
Apr 24, 2012
Messages
24
Gender
Male
HSC
2014
Re: 2012 Year 9 &10 Mathematics Marathon

So many now. Lol I shall do them tonight
 

kazemagic

Member
Joined
Feb 8, 2012
Messages
626
Gender
Male
HSC
2014
Re: 2012 Year 9 &10 Mathematics Marathon

Ymcaec correct :D

so you let x = that massive equation.

square both sides so..

x^2 = 7 - 6[insert that massive equation]

the massive equation = x

hence: x^2 = 7 - 6x
x^2 + 6x - 7 = 0
(x+7)(x-1)=0
x = -7 or 1
but because x>=0 because its a square root
therefore x=1
Correct too :)
 

Demento1

Philosopher.
Joined
Dec 23, 2011
Messages
866
Location
Sydney
Gender
Male
HSC
2014
Re: 2012 Year 9 &10 Mathematics Marathon

So, back from table tennis training. What I have gathered from this maths marathon thread: If ymcaec really is a year 10 student, then the person is quite impressive.
 
Joined
Apr 1, 2011
Messages
1,012
Location
District 12
Gender
Male
HSC
2013
Re: 2012 Year 9 &10 Mathematics Marathon

So, back from table tennis training. What I have gathered from this maths marathon thread: If ymcaec really is a year 10 student, then the person is quite impressive.
agreed :D

(please do my question *hint hint*) :p
 

Demento1

Philosopher.
Joined
Dec 23, 2011
Messages
866
Location
Sydney
Gender
Male
HSC
2014
Re: 2012 Year 9 &10 Mathematics Marathon

agreed :D

(please do my question *hint hint*) :p
Will do, gimme a few minutes. I'm quite a novice at LaTeXing and I take a long time to do that. The typing is going to consume most of my time.
 

Demento1

Philosopher.
Joined
Dec 23, 2011
Messages
866
Location
Sydney
Gender
Male
HSC
2014
Re: 2012 Year 9 &10 Mathematics Marathon

Here is one of the last questions in my yearly, have fun!

Obviously for c)i) All it requires is the use of sine rule:

Then: We are given that

Edit: Haha, my typing speed is godly to ymcaec.
 

Demento1

Philosopher.
Joined
Dec 23, 2011
Messages
866
Location
Sydney
Gender
Male
HSC
2014
Re: 2012 Year 9 &10 Mathematics Marathon

For c)ii) It is simply asking for a pythagorean method: Thus having the equation,







Edit: Typed it wrong.
 
Last edited:

ymcaec

Member
Joined
Apr 25, 2012
Messages
77
Gender
Undisclosed
HSC
N/A
Re: 2012 Year 9 &10 Mathematics Marathon

iii. 4:9
not typing out the whole working out ... hate latex...
 

Demento1

Philosopher.
Joined
Dec 23, 2011
Messages
866
Location
Sydney
Gender
Male
HSC
2014
Re: 2012 Year 9 &10 Mathematics Marathon

For c)iii) You had to simply express the volume of the sphere over the cone. This was extremely painful to type. I probably typed it wrong somewhere.



Eventually, you'll get:

 
Joined
Apr 1, 2011
Messages
1,012
Location
District 12
Gender
Male
HSC
2013
Re: 2012 Year 9 &10 Mathematics Marathon

For c)iii) You had to simply express the volume of the sphere over the cone. This was extremely painful to type. I probably typed it wrong somewhere.



Eventually, you'll get:

I know that feel, it was already annoying to write all of that in exam conditions let alone latexing lol..
 

Demento1

Philosopher.
Joined
Dec 23, 2011
Messages
866
Location
Sydney
Gender
Male
HSC
2014
Re: 2012 Year 9 &10 Mathematics Marathon

For c)iv) There is no way in hell i'm going to latex my working out. Although I can say that all you have to do is find the ratio of the volume of the cone inside the sphere. Then you'll get your answer and compare the ratios of the two. The one which is larger, means that more space is covered within that volume. I believe the sphere inside the cone occupies more space.
 

Demento1

Philosopher.
Joined
Dec 23, 2011
Messages
866
Location
Sydney
Gender
Male
HSC
2014
Re: 2012 Year 9 &10 Mathematics Marathon

I know that feel, it was already annoying to write all of that in exam conditions let alone latexing lol..
What I have found, ~75% of the time I took to answer your Qs came from the latexing.
 
Joined
Apr 1, 2011
Messages
1,012
Location
District 12
Gender
Male
HSC
2013
Re: 2012 Year 9 &10 Mathematics Marathon

For c)iv) There is no way in hell i'm going to latex my working out. Although I can say that all you have to do is find the ratio of the volume of the cone inside the sphere. Then you'll get your answer and compare the ratios of the two. The one which is larger, means that more space is covered within that volume. I believe the sphere inside the cone occupies more space.
Correct! Sorry for the Latex torture lol
Here are the actual solutions for part iv. if anyone wants a look

PFZU5.png
 

Demento1

Philosopher.
Joined
Dec 23, 2011
Messages
866
Location
Sydney
Gender
Male
HSC
2014
Re: 2012 Year 9 &10 Mathematics Marathon

Correct! Sorry for the Latex torture lol
Here are the actual solutions for part iv. if anyone wants a look

View attachment 25783
Yeah, basically Thus you just see which one occupied more space. Good question by the way, it actually asked for people to utilise more then simply geometrical applications.

Edit: Here's a question I personally liked when I did it back in year 9. It can be quite easy if you think a little outside the box:

A point P lies inside a square ABCD of side 120. Let F be a point on CD so that PF is perpendicular to CD. P is equidistant from A, B, F. Find PA.
 
Last edited:

TerenceM

New Member
Joined
Apr 24, 2012
Messages
24
Gender
Male
HSC
2014
Re: 2012 Year 9 &10 Mathematics Marathon

Nice 100th post LOL xD (Y)
 

Users Who Are Viewing This Thread (Users: 0, Guests: 2)

Top