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March 29, 2024, 01:28:24 am

Author Topic: 4U Maths Question Thread  (Read 659828 times)  Share 

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RuiAce

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Re: 4U Maths Question Thread
« Reply #855 on: February 21, 2017, 11:02:44 pm »
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Heyyyy I keep forgetting how to do this question someone please help hahaha ty


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RuiAce

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Re: 4U Maths Question Thread
« Reply #856 on: February 21, 2017, 11:04:58 pm »
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please help
Hint: Use trigonometry.

Use a right angled triangle and the fact cos is the adjacent side divided by the hypotenuse. Then, use the rule of ASTC (cosine is positive in the 4th quadrant)

(Alternatively, use the parametric definition of the circle)

Kle123

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Re: 4U Maths Question Thread
« Reply #857 on: February 22, 2017, 12:43:27 am »
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I don't know/forgot how to do this question. Please help. Doing 1part is sufficient (then i can do the other as both questions are similar,,,, probably?). Thank you

RuiAce

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Re: 4U Maths Question Thread
« Reply #858 on: February 22, 2017, 01:20:35 am »
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I don't know/forgot how to do this question. Please help. Doing 1part is sufficient (then i can do the other as both questions are similar,,,, probably?). Thank you
Somewhat untidy.







Kle123

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Re: 4U Maths Question Thread
« Reply #859 on: February 22, 2017, 08:53:32 am »
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Thank you night owl Rui.  :D

michaelalt

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Re: 4U Maths Question Thread
« Reply #860 on: February 22, 2017, 09:14:51 am »
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Just what I wrote above; when we divide two complex numbers in cis notation, we divide their modulus and subtract their argument. So,



You can use this to get the final answer

Like this?

jamonwindeyer

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Re: 4U Maths Question Thread
« Reply #861 on: February 22, 2017, 09:21:52 am »
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Like this?

Looks perfect to me ;D well done!!

michaelalt

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Re: 4U Maths Question Thread
« Reply #862 on: February 22, 2017, 09:31:17 am »
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Looks perfect to me ;D well done!!

The answers say 3π/10 though so I don't know where I went wrong.

jakesilove

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Re: 4U Maths Question Thread
« Reply #863 on: February 22, 2017, 10:25:55 am »
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The answers say 3π/10 though so I don't know where I went wrong.

Remember; on the Argand diagram, you can add or subtract 2*pi without it changing the answer! This is because the point goes 'full circle'. In fact, the HSC prefers that you write your arguments between -Pi and Pi. In this case, subtract 20*pi/10 (ie. 2*pi) to get the answer you're looking for :)
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michaelalt

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Re: 4U Maths Question Thread
« Reply #864 on: February 22, 2017, 10:29:47 am »
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Remember; on the Argand diagram, you can add or subtract 2*pi without it changing the answer! This is because the point goes 'full circle'. In fact, the HSC prefers that you write your arguments between -Pi and Pi. In this case, subtract 20*pi/10 (ie. 2*pi) to get the answer you're looking for :)

OHH yea. How does it come so easily to you haha, thank you again Jake!

jakesilove

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Re: 4U Maths Question Thread
« Reply #865 on: February 22, 2017, 10:31:01 am »
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OHH yea. How does it come so easily to you haha, thank you again Jake!

Don't worry buddy, once you've had enough practice it'll come easily to you as well! For now, this shit is hard.
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michaelalt

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Re: 4U Maths Question Thread
« Reply #866 on: February 22, 2017, 01:20:36 pm »
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Is someone able to help me with one of these questions? I don't remember the pattern.

Kle123

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Re: 4U Maths Question Thread
« Reply #867 on: February 22, 2017, 05:29:43 pm »
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I don't see how part i) is related to ii). Soooo stressful. Please help, thanks again.

Kle123

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Re: 4U Maths Question Thread
« Reply #868 on: February 22, 2017, 06:27:59 pm »
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Is someone able to help me with one of these questions? I don't remember the pattern.
I've only shown working out in the first question. The rest are answers (if you were already given answers, this is quite useless). I don't think exam questions require working out, however i might be wrong. I've done all the questions as mostly those questions given are different and there is no specific pattern (not really a pattern).

side note: there are a set amount of locus sketches and if you learn them all this section of complex numbers should be a cruise

RuiAce

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Re: 4U Maths Question Thread
« Reply #869 on: February 22, 2017, 06:39:01 pm »
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I don't see how part i) is related to ii). Soooo stressful. Please help, thanks again.







« Last Edit: February 22, 2017, 06:46:33 pm by RuiAce »