ATAR Notes: Forum

Archived Discussion => Mathematics => 2011 => End-of-year exams => Exam Discussion => Victoria => Further Mathematics => Topic started by: Ematuro on November 04, 2011, 01:54:56 pm

Title: Trigonometry question 9?
Post by: Ematuro on November 04, 2011, 01:54:56 pm
What did you guys all get for that? I got E but a lot of my friends said D. That was probably the most challenging question in the trig module D:
Title: Re: Trigonometry question 9?
Post by: spinaway on November 04, 2011, 01:58:29 pm
i got e too  :-\
Title: Re: Trigonometry question 9?
Post by: Ematuro on November 04, 2011, 01:59:22 pm
Okay I just worked it out to be D.... I hope I'm wrong D:
Title: Re: Trigonometry question 9?
Post by: butene on November 04, 2011, 02:01:27 pm
Hmm i got E as well
Title: Re: Trigonometry question 9?
Post by: arock on November 04, 2011, 02:09:57 pm
I got D.
Title: Re: Trigonometry question 9?
Post by: Tashi on November 04, 2011, 02:11:48 pm
You had to flip the triangle and then you get k=40/24. I kept tossing up between D and E because I didn't know but I'm pretty sure it's D.
Title: Re: Trigonometry question 9?
Post by: Ematuro on November 04, 2011, 02:12:23 pm
Yeah pretty sure its D too. Similar triangles eh? So shattered..
Title: Re: Trigonometry question 9?
Post by: MicroShift on November 04, 2011, 02:15:03 pm
Are you kidding me? They were similar triangles? Fuck, I spent 20 minutes on that question at the end trying to work it out and ended up with D by working back from the information given.
I really hope it was D.
Title: Re: Trigonometry question 9?
Post by: Bigkev93 on November 04, 2011, 02:16:14 pm
answers by itute:

Data Analysis
1C 2E 3C 4C 5E 6E 7A 8A 9B 10C 11D 12E 13D

Number Patterns
1C 2A 3D 4C 5D 6B 7E 8A 9D

gEOMETRY & tRIGONOMETRY
1D 2A 3C 4C 5D 6D 7B 8D 9D

Graphs & Relations
1B 2C 3A 4A 5B 6D 7E 8C 9E


apparently its D :( i did E though.
Title: Re: Trigonometry question 9?
Post by: Tashi on November 04, 2011, 02:27:02 pm
Pretty sure I got 38/40 lol dammit.
Title: Re: Trigonometry question 9?
Post by: Bigkev93 on November 04, 2011, 02:47:02 pm
same here, if i got the last trig right,
Title: Re: Trigonometry question 9?
Post by: cammy on November 04, 2011, 04:48:05 pm
has anyone got the matrices answers?
Title: Re: Trigonometry question 9?
Post by: cammy on November 04, 2011, 04:48:53 pm
oh wait there is another thread. apologies
Title: Re: Trigonometry question 9?
Post by: Bigkev93 on November 04, 2011, 06:35:26 pm
The answer is definately E for question 9 in trig.
You have to add 100 to the answer you get with final answer you get with similar triangles.
I have cross checked with around 2 teachers.
And did it myself 2-3 times, so yeh.
Title: Re: Trigonometry question 9?
Post by: BubbleWrapMan on November 04, 2011, 09:29:18 pm
ABD is similar to ACB, as they share theta and angle BAC.
Title: Re: Trigonometry question 9?
Post by: xdecay on November 04, 2011, 09:34:12 pm
I got D because I thought that VCAA might try to trick the students who got 178 and forgot to add 100 at the end so I guessed that 278 was the correct answer but then I realized if it was similar triangles it wouldn't make much sense. I think there was no logic at the reason behind my chosen answer (and this post isn't making much sense), but yes, I chose D.
Title: Re: Trigonometry question 9?
Post by: Ematuro on November 04, 2011, 09:40:15 pm
I got D because I thought that VCAA might try to trick the students who got 178 and forgot to add 100 at the end so I guessed that 278 was the correct answer but then I realized if it was similar triangles it wouldn't make much sense. I think there was no logic at the reason behind my chosen answer (and this post isn't making much sense), but yes, I chose D.

LOL. Exactly what I thought but I added the 100 to 278 and got E.
Title: Re: Trigonometry question 9?
Post by: iliketurtles on November 04, 2011, 09:46:09 pm
I chose A.
And I seem to be the only person in the state to do so.
FML.
Title: Re: Trigonometry question 9?
Post by: davidle_10 on November 05, 2011, 09:46:41 am
D is the correct answer. because ABD is similar to ABC. That means if you worked out the triangle ABC to be 378 then the triangle CBD must have been 278 which cannot be determined.
Title: Re: Trigonometry question 9?
Post by: arock on November 05, 2011, 11:31:19 am
D is the correct answer. because ABD is similar to ABC. That means if you worked out the triangle ABC to be 378 then the triangle CBD must have been 278 which cannot be determined.
ACB is similar to ABD rather
Title: Re: Trigonometry question 9?
Post by: Bigkev93 on November 05, 2011, 04:41:00 pm
this question is just fked up :S it doesnt make sense, meh.
I hope exam 2 is better.
Title: Re: Trigonometry question 9?
Post by: Wezanator123 on November 06, 2011, 05:00:12 pm
For Geo and trig Q8. what did people put ? My friend told me it was C) (apparently)

Title: Re: Trigonometry question 9?
Post by: MJRomeo81 on November 06, 2011, 05:03:09 pm
I'm actually surprised I got this one right. The working out was relatively simple for a Q9 in a module...nevertheless I still only scored 5/9 for trig :(
Title: Re: Trigonometry question 9?
Post by: odessa on November 06, 2011, 07:15:18 pm
9 for trig - is D - we got it checked by a spec teacher
Title: Re: Trigonometry question 9?
Post by: nerdgasm on November 06, 2011, 07:32:15 pm
I think the answer to Question 9 is D, (my working is shown in the attached document, using similar triangles and Heron's formula).

In general, if two triangles are similar, the ratio of their side lengths is the square root of the ratio of their areas.

Hence, since the sides of Triangle ABC are 5/3 of the sides of Triangle ABD, it follows that the area of Triangle ABC is 25/9 of the area of Triangle ABD, and hence, the area of Triangle ABC is
100(25/9) = 277.777, closest to answer D.