Tech. Drawing analysis

OTliddy

I thought that was quite tricky. Heres what I did:
Q1:Got everythibg apart from (c), which i half did.
Q3:Got this done, exept for detirmining the anlge between the vertical and horizontal planes on the new plane. I thought it was always 90`?
Q4:A predictable question. I got very mixed up towards the end and didnt know what went where, but i got most of the turning/penetration points.
Q7: A bit af a disaster. Normally my most reliably question. Ended up drawing completly random lines for part (c). Did anyone get the pyramid for part(a) going though the line TH in the plan?

Q1: Got everything right I think. I just looked at (c) and it just clicked! The best question I did by far.

Q3: I thought I did that very well, but I got a tiny cone with a HUGE height, so I'm not sure if it's right. Did anyone else get this?

Q4: Did this very well too. May have put some dotted lines in that should have been full, but besides that I nailed it!

Q5: I thought I did this really well, but when I got home I realised that I made two stupid mistakes, and I'm not going to embarass myself by saying what they were. Because of this, I say it was my worst question.



Sorry to hear about Q7 OTliddy. I just looked at it, and went back to the other questions. It seemed really hard.


Overall, I think I got a A2/B1. I got the exam done an hour early, and left the school feeling really confident.

The Failed God

Yuck Horrible paper, did 1) Got it all out i think.. 2) Took me a while cause i didnt see the obvious tangent so i did a locus which worked so i presume il get the marks.. 3)Dirty question, couldnt do part b so i hard to sketch part c.. 6) Grand question, messed up par b but i prob got most marks.. PLEASE GIVE Me AN EASY PAPER 2!!!

*Angel*

Deleted User wrote:

Q3: I thought I did that very well, but I got a tiny cone with a HUGE height, so I'm not sure if it's right. Did anyone else get this?

That's not what I got...

I started off with Q3 very straightforward I thought (20mins), Q6 was another short Q. Then I did Q7, parts (a) and (b) were straightforward enough, (c) was a little confusing, it took a while but I think I got it in the end. Then Q4 was grand.

Overall I think it was an ok of a paper, I've heard that Q1 (even part c) was the easiest, maybe I should have done it :rolleyes: .

StupidLikeAFox

:(:(:(:(:(

Got the interpenetration question completely right, A1 for sure. Got (a) and (b) of question 1 right. the rest was just

*Angel*

OTliddy wrote:

Q3:Got this done, exept for detirmining the anlge between the vertical and horizontal planes on the new plane. I thought it was always 90`?

It would only be worth a few marks anyway.

OTliddy wrote:

Q7: A bit af a disaster. Normally my most reliably question. Ended up drawing completly random lines for part (c). Did anyone get the pyramid for part(a) going though the line TH in the plan?

Yeah.

jacksie

Q1 - All apart from (c)

Q3 - (a)no bother
(b)Got a very high cone.. think it was right though
(c)Didnt get angle

Q4 - Got most of it done

Q5 - Easy!

jacksie

jacksie wrote:

(b)Got a very high cone.. think it was right though

I knew it! A lot of my friends got that too!!!

*Angel*

If the cone was high it would also be wide, cos if you think that it had to be tangental to the sphere at a point 33mm above the hp then the side of the cone wouldn't have a very steep slope.

You do realise that finding the true angle between the vt and ht is a common enough question in hyperbolic parabloids too, just to warn you.

*Angel*

*Angel* wrote:

If the cone was high it would also be wide, cos if you think that it had to be tangental to the sphere at a point 33mm above the hp then the side of the cone wouldn't have a very steep slope.

You do realise that finding the true angle between the vt and ht is a common enough question in hyperbolic parabloids too, just to warn you.

Not necessiarily. When you draw the horizontal line 33mm above the ground, and then bring it down to plan, you will see that the the point of contact is very close to the edge of the sphere. We know that cone is a tangent to the other cone in the plan (as they touch the ground), so if you get the locus, you will see that it is a very small circle that is a tangent to the cone in plan and in which the point of contact is very close to the edge of the circle.When we find the locaton of the point of contact between the new cone and the sphere in elevation, you will see that it is very close to the edge of the cone (about 1mm in). So therefore the line would be VERY obtuse, as the sides of the cone would have to be inside this point of contact for it to make sense, so therefore it makes cery steep sides for the cone.

Tbh, I just read that and I haven't a clue what I'm on about! It's very hard to describe without a diagram.

*Angel*

Deleted User wrote:

Not necessiarily. When you draw the horizontal line 33mm above the ground, and then bring it down to plan, you will see that the the point of contact is very close to the edge of the sphere. We know that cone is a tangent to the other cone in the plan (as they touch the ground), so if you get the locus, you will see that it is a very small circle that is a tangent to the cone in plan and in which the point of contact is very close to the edge of the circle.When we find the locaton of the point of contact between the new cone and the sphere in elevation, you will see that it is very close to the edge of the cone (about 1mm in). So therefore the line would be VERY obtuse, as the sides of the cone would have to be inside this point of contact for it to make sense, so therefore it makes cery steep sides for the cone.

I disagree with your thin cone and you're confusing. However let it be, sure it doesn't matter now anyway (not really). TD shouldn't be explained in words anyhoo.

*Angel*

*Angel* wrote:

I disagree with your thin cone and you're confusing. However let it be, sure it doesn't matter now anyway (not really). TD shouldn't be explained in words anyhoo.

Yeah i confused myself too!

Well if it is wrong, then it seems that a lot of people did it that way, so we should get a lot of marks. Same thing goes if you're wrong.

Anyway, best of luck tomorrow!

*Angel*

But I'm not wrong (prob will be now)

Yeah good luck to all the Tech Drawers out there.

Breezer

Q1 mostly right (at least half of part c, maybe more)

Q2 fine except I made it ten times more difficult by not reading the question. Instead of making one chord twice the other one I did an "angle at the centre is twice the angle at the circumference when standing on the same arc" job on it

Q5 my locus went through the ground (!) but I'm hoping I just messed up a point or something.

Q6 everything except the tangent to the parabola, which is annoying cuz it was an entire part and this is supposed to be my best question.

Roll on paper 2 and please be easy!

Cina

Hmm, it was most certainly not a very high cone for Q3. I had that at first aswell but then i realised I was doing my lokai off the wrong points and the final cone worked out to be about 25mm smaller than Cone A. Touching the sphere 33mm above the ground and in contact with the Cone at point P.

*Angel*

Cina wrote:

Hmm, it was most certainly not a very high cone for Q3. I had that at first aswell but then i realised I was doing my lokai off the wrong points and the final cone worked out to be about 25mm smaller than Cone A. Touching the sphere 33mm above the ground and in contact with the Cone at point P.

Yey I'm now backed up.

Damn it!!!

Well a lot of people made that mistake so hopefully they'll be nice when they correct it!!


Anyway, best of luck tomorrow Cina.

OTliddy

I wouldnt describe my cone as very high, but I think it was a bit higher than cone A. Damm!...ye all seemed to have done so well...i was hoping for an A between the 2 papers but that seems to be out the window now .

*Angel*

Out of interest is their many girls in your td classes, in mine there is one 5 out of around 24. Which I think is pretty pathetic.

*Angel*

OTliddy wrote:

I wouldnt describe my cone as very high, but I think it was a bit higher than cone A. Damm!...ye all seemed to have done so well...i was hoping for an A between the 2 papers but that seems to be out the window now .

Hope is not lost, you can still lose 60 marks between the papers and still get an A.

OTliddy

In my class of 15(around) there are no girls. However, in my music class, there is only one other boy

*Angel*

OTliddy wrote:

In my class of 15(around) there are no girls. However, in my music class, there is only one other boy

Terrible! You're so deprived. It's kinda weird how certain subjects don't appeal to different sexes.

OTliddy

*Angel* wrote:

Terrible! You're so deprived. It's kinda weird how certain subjects don't appeal to different sexes.

Yeah, it happens in extremes. In physics class if 17, there are 3 girls.
There are 40 people in the year doing music,only 4 of whom are boys.
Strangely, i got put in high female Irish and English classes. In both there are about 25 people of only 4 are boys. I'm not complaining.

sock.rocker*

Cina wrote:

Hmm, it was most certainly not a very high cone for Q3. I had that at first aswell but then i realised I was doing my lokai off the wrong points and the final cone worked out to be about 25mm smaller than Cone A. Touching the sphere 33mm above the ground and in contact with the Cone at point P.

yeah, i got that too.. i knew the logic of doin that question but the first time i tryied, i was takin the locus from the wrong points which gave me the high cone people are on about here

i went back to it though, restarted and got it out..

to get the true angle, do ya take an auxilary along the horizontal trace? thats what i did.. bout 60 degrees i think

Beno

Q1 (C) i drew a horz line from d to edge abc then brought that back to plan which gave me a line through plane abc

Then i drew a cone 40d from plane abc to d. Then i drew a xy parllel to plane abc where i got a circle from the cone
Bring these heights back from circle to abc then to the plan which should give you an elipse in plan
There this cuts the first line you drew on abc in the plan gives you the point where it hits the plane abc. Bingo you have ur line
That how i did it anyway
Fairly happy with the paper, stayed to the very end (examiner gave us an extra 20min) only did 4 q though couldnt do 7

P.s my new cone was about 20 higher than the other one and about the same diameter

Beno

Beno wrote:

Q1 (C) i drew a horz line from d to edge abc then brought that back to plan which gave me a line through plane abc

Then i drew a cone 40d from plane abc to d. Then i drew a xy parllel to plane abc where i got a circle from the cone
Bring these heights back from circle to abc then to the plan which should give you an elipse in plan
There this cuts the first line you drew on abc in the plan gives you the point where it hits the plane abc. Bingo you have ur line
That how i did it anyway

That sounds familiar!


But you examiner gave you an extra 20 minutes? Wtf?!

Beno

she was a bit busy with all the bags and papers and talkin to a couple of the lads about how they did next thing u knew it was 10 to

*Angel*

Beno wrote:

examiner gave us an extra 20min

Nice for some, I would have done an extra question.

Beno

spent 30min lookin at Q7 but just couldnt do it

sock.rocker*

Q7 was good except for the very end.. cudnt get the other pyramid at all.

*Angel*

sock.rocker* wrote:

Q7 was good except for the very end.. cudnt get the other pyramid at all.

I thought before hand that the oblique would be quite hard, however I was surprised with when I first looked at it I thought it looked easy, 'a' and 'b' were, then I saw 'c' and it was couldn't actually believe they'd thrown that in, it made the question quite a lot longer, thankfully I had time to spend a while on it, and I'm pretty sure I got it in the end, definitely a bit :eek: though.