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July 24, 2025, 03:39:03 am

Author Topic: VCE Specialist 3/4 Question Thread!  (Read 2549139 times)  Share 

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507

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Re: Specialist 3/4 Question Thread!
« Reply #1260 on: February 08, 2013, 07:47:03 pm »
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b) I'm getting

Answer from the book says

Am I doing something wrong, or did the authour just accidentally multiply by rather than .

Thanks

polar

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Re: Specialist 3/4 Question Thread!
« Reply #1261 on: February 08, 2013, 07:56:05 pm »
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b) I'm getting

Answer from the book says

Am I doing something wrong, or did the authour just accidentally multiply by rather than .

Thanks

so, you know that the vector you want is
first, lets work out the unit vector of a:

next, work out the magnitude of b:

now, multiplying these gives

507

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Re: Specialist 3/4 Question Thread!
« Reply #1262 on: February 08, 2013, 07:59:31 pm »
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so, you know that the vector you want is
first, lets work out the unit vector of a:

next, work out the magnitude of b:

now, multiplying these gives

Oh that was dumb lol. Accidentally found from the previous question :P
Thanks :)
« Last Edit: February 08, 2013, 08:02:36 pm by 507 »

saba.ay

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Re: Specialist 3/4 Question Thread!
« Reply #1263 on: February 09, 2013, 03:36:16 pm »
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This is gonna be a very stupid question, but how would I do the following:
Find the Cartesian equation of the circle:
x=3 cos (2t) , y = 3 sin (2t) , given that 't' belongs to [0, pi]

I don't know how to deal with the '2t' seeing as we've only been shown questions with only t? :/

Homer

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Re: Specialist 3/4 Question Thread!
« Reply #1264 on: February 09, 2013, 03:46:33 pm »
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How would I differentiate 1\(1+x^2)
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polar

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Re: Specialist 3/4 Question Thread!
« Reply #1265 on: February 09, 2013, 03:53:45 pm »
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This is gonna be a very stupid question, but how would I do the following:
Find the Cartesian equation of the circle:
x=3 cos (2t) , y = 3 sin (2t) , given that 't' belongs to [0, pi]

I don't know how to deal with the '2t' seeing as we've only been shown questions with only t? :/

,

it doesn't matter what's inside the brackets (provided it's defined of course)

- always check the domain as well to see how much of the path you need to draw , hence this gives a full circle
- you can't really see what effect the 2t has, but it makes travelling along the path a bit 'faster', but doesn't have any effect on the shape of the path (t takes to make a whole circle, 2t takes )
- you still get
and

since
How would I differentiate 1\(1+x^2)

use the quotient rule
« Last Edit: February 09, 2013, 04:01:32 pm by polar »

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Re: Specialist 3/4 Question Thread!
« Reply #1266 on: February 09, 2013, 04:13:07 pm »
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Oh yeah haha what a dummy! Must have had a mental blank :-/
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Re: Specialist 3/4 Question Thread!
« Reply #1267 on: February 10, 2013, 05:26:21 pm »
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Can somebody help me with the following vectors question from the Essentials textbook?

ABC is a right-angled triangle with the right angle at B. If AC = 2i + 4j and AB is parallel to i + j, find AB.

507

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Re: Specialist 3/4 Question Thread!
« Reply #1268 on: February 10, 2013, 05:48:36 pm »
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Can somebody help me with the following vectors question from the Essentials textbook?

ABC is a right-angled triangle with the right angle at B. If AC = 2i + 4j and AB is parallel to i + j, find AB.

Since is parallel to ,



Also,



(perpendicular to one another)

Therefore,





Isn't applicable as the dot product only applies to non-zero vectors.

So

I'll try to fix the latex up a bit lol.
« Last Edit: February 10, 2013, 06:24:34 pm by 507 »

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Re: Specialist 3/4 Question Thread!
« Reply #1269 on: February 10, 2013, 05:52:14 pm »
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Hmm... I was going to suggest generating three equations and solving them simultaneously, but that method is much more efficient. :)
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Re: Specialist 3/4 Question Thread!
« Reply #1270 on: February 10, 2013, 06:20:28 pm »
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Can somebody help me with the following vectors question from the Essentials textbook?

ABC is a right-angled triangle with the right angle at B. If AC = 2i + 4j and AB is parallel to i + j, find AB.

I think you can also use vector resolutes to solve this.

Let b = i + j








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Re: Specialist 3/4 Question Thread!
« Reply #1271 on: February 11, 2013, 06:14:39 pm »
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Just stuck on part e. :)
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Re: Specialist 3/4 Question Thread!
« Reply #1272 on: February 11, 2013, 06:58:55 pm »
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Hint: if a circle with centre Q goes through E, D, B and F, that means QE, QD, QB and QF are all radii, and must have the same magnitude.
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507

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Re: Specialist 3/4 Question Thread!
« Reply #1273 on: February 11, 2013, 07:05:22 pm »
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Think of the coefficient of to be like an x co-ordinate, and the coefficient of to be a y co-ordinate.

So = the point
=
=

Sub these values into and solve simultaneously.
Giving you the equation
CP is
Which can be expressed as the vector

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Re: Specialist 3/4 Question Thread!
« Reply #1274 on: February 11, 2013, 07:13:18 pm »
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(Image removed from quote.)

Just stuck on part e. :)

or think that the angles EDF and EBF are right angles which means EF is the diameter of the circle. The midpoint of EF is C.