Who got the cone of death question

[Blakhitman]

From memory there was one of these similar triangles related rates questions in the DH book or at least one was discussed at the lecture last year for Methods.

My friend said he used similar cylinders...

Lol... how would that work... I'm visualising it at the moment and all I see is fail.. xD

yet he got r=5/3 cm

[funkyducky]

When we were learning related rates my methods teacher specifically told us to watch out for similar triangles and cones with related rates questions. At the time, I didn't really get why, but it came up A LOT during my exam revision, although usually it was simpler than the cone of death - more like an inverted cone being filled with liquid, the similar triangles is a lot easier to see than with a cylinder inscribed in a cone. But yeah, I'm pretty sure similar triangles is year 7 or 8-level maths...I remember  hating them when I was younger.

[Spacehippy]

yeah. didnt get it. got to r = 0 for part c, couldnt understand, knew it needed similar triangles but didnt realise it was different from how i was looking at it silly consequentiality.

[dirty_commie]

The bastards could have at least made it a 'show that' question.

[Spacehippy]

exactly. were there even any show thats on the exam?

[sajib_mostofa]

exactly. were there even any show thats on the exam?

Nope.

[Stroodle]

Seems to me that for the last few years vcaa has had a tendency to put the questions that'll separate the students at the very end of the paper.

[scatteam_2]

didnt get the question
good byeeeeeeee 5 marks

[eddie10]

I spent 25 minutes on it lol.. during reading nothing was obvious to me, so I knew it was going to be like that.
Similar triangles were completely out of mind.. So I went with the simple long option:
Area => (1/2)*5*2 equal to the sum of r*h and the remaining two triangles.
So
5  = (r*h) + (1/2)*(5-h)*(r) + (1/2)*(2-r)*(h)
5  = r*h + 5r/2 - (r*h)/2 + 2h/2 - (r*h)/2
10 = 5r + 2h
2h = 10 - 5r
h  = (10-5r)/2
Worked eventually lol.
Apparently it's (part of) the proof for similar triangles.

[iNerd]

Don't where else to put this..
MHS 2010 Technology-Free Year 10 maths.....freaking 'cone of death' question worth 8 marks.
I have a bad feeling that the teachers saw the methods exam and decided to insert a dumbed-down version in our exam to prepare us for VCE 

[sheno]

Don't where else to put this..
MHS 2010 Technology-Free Year 10 maths.....freaking 'cone of death' question worth 8 marks.
I have a bad feeling that the teachers saw the methods exam and decided to insert a dumbed-down version in our exam to prepare us for VCE 

nice work
but when you do methods 3/4 ... vcaa will cook up something new and nasty that will have nothing to do with triangles