Specialist 1/2 Question Thread!

[RuiAce]

Dumb question alert!

I'm not too sure if I recall this question, but it's been baffling me:
If z=-4i what is the modulus-argument of Iz^3I

Wouldn't the modulus be 64 and the argument be 0?
However the teacher said that the argument was pi/2

Please help this poor soul

Edit: Just saw the bars around Iz^3I. Was that intended?
If yes then the argument is certainly 0 because the modulus is a real number

[pha0015]

Edit: Just saw the bars around Iz^3I. Was that intended?
If yes then the argument is certainly 0 because the modulus is a real number

Edit: Just saw the bars around Iz^3I. Was that intended?
If yes then the argument is certainly 0 because the modulus is a real number

I do remember seeing the modulus signs, but I don't fully recall the wording of the question, so it may have been something like: if the modulus is Iz^3I then...

Thanks for the clarification anyways

[keltingmeith]

Dumb question alert!

I'm not too sure if I recall this question, but it's been baffling me:
If z=-4i what is the modulus-argument of Iz^3I

Wouldn't the modulus be 64 and the argument be 0?
However the teacher said that the argument was pi/2

Please help this poor soul

Interesting - not sure you've gone and calculated the argument for this, but there's two ways to look at it. The first is "what is the modulus and argument of the number |z^3| (the modulus of z^3)", in which case |z^3| is (by definition) a real number, and the argument MUST be 0, as you've initially suggested.

The second (and I imagine this is where the teacher was going), is where you ignore the modulus signs, and she actually intended you to find the modulus and argument of z^3 - the complex number. The modulus is, of course, done the same, but now for the argument, you'd need to use the formula arg(z^n)=n*arg(z), and then normalise it so it's in the domain (-pi,pi].

[magicmania121]

Hi can someone give me any good suggestions for a specialist tutor, I really wanna start now

[Sine]

Hi can someone give me any good suggestions for a specialist tutor, I really wanna start now

derrick ha, usually he only does yearly intakes and only at a unit 3/4 level. However you need to get in pretty early to secure a place. Otherwise check out anyone found HERE

[atarmaths77]

Does anyone know how to model the heartbeat ekg using trigonometry, using e^(-x^2), where you multiply a sine or cosine function by another trigonometric function to look like this: https://malouffsaandpblog.files.wordpress.com/2013/03/trevor-ekg.jpg

[magicmania121]

Does anyon have the worked solutions for the book

[keltingmeith]

Does anyone know how to model the heartbeat ekg using trigonometry, using e^(-x^2), where you multiply a sine or cosine function by another trigonometric function to look like this: https://malouffsaandpblog.files.wordpress.com/2013/03/trevor-ekg.jpg

Not in a way accessible to VCE, other than randomly guessing. Is this for an assignment?

Does anyon have the worked solutions for the book

Which book? You can probably purchase them directly from the publisher if you can't find them anywhere else.

[magicmania121]

It's the specialist unit 1/2 book

[keltingmeith]

It's the specialist unit 1/2 book

I mean, that's cool, but there's a few of them. Which publisher is it?

[magicmania121]

It's the Cambridge one like it is blue

[Sine]

It's the specialist unit 1/2 book

It's the Cambridge one like it is blue

Does anyon have the worked solutions for the book

Sorry unfortunately we cannot post copyright material on the forums

Your teacher should have access to the worked solutions so ask them.

Hopefully this helps

[keltingmeith]

Unfortunately, a quick Google search tells me that the worked solutions may not be available to purchase. I recommend following Sine's suggestion.

[A TART]

Hi I've been able to do this vector question and get the correct answer, however, I've been doing under the assumption the angle between the two is 0 (going in same direction). Can someone explain why this happens? Or am I wrong in my working out?
http://i.imgur.com/Q0ce9bp.jpg

[VanillaRice]

Hi I've been able to do this vector question and get the correct answer, however, I've been doing under the assumption the angle between the two is 0 (going in same direction). Can someone explain why this happens? Or am I wrong in my working out?
http://i.imgur.com/Q0ce9bp.jpg

You don't need to substitute a dot b in this case (you can, but a there is a simpler method). The dot product works very much like multiplication, so we can use that property in this question.
i.e.

With this in mind, have another go at the question. The most likely reason you are able to substitute theta = 0 is that when you do so, you are assuming the angle between a and b is 0, and also that the angle between a and (a+b) is 0 - note the two dot products are not the same.

Hope this helps