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March 30, 2024, 01:03:11 am

Author Topic: 3U Maths Question Thread  (Read 1230716 times)  Share 

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katherine123

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Re: 3U Maths Question Thread
« Reply #90 on: March 29, 2016, 09:38:08 pm »
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why is it   10C7(1/4)^7(3/4)3           not just (1/4)^7(3/4)3
               C=combination

ATWalk

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Re: 3U Maths Question Thread
« Reply #91 on: March 29, 2016, 10:04:33 pm »
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Hi all,
Really struggling with part C of this 3D trig question, I just can't seem to get it out...
Help would be very much appreciated!

Thankyou!!  :)

Hey, here's my solution. Sorry I had to upload in two photos because of file size limits. Also, sorry if it's a bit messy, I find 3D trig questions like this hard to do neatly. If you're confused feel free to reply again. Happy to help.

RuiAce

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Re: 3U Maths Question Thread
« Reply #92 on: March 30, 2016, 12:19:41 am »
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Hi all,
Really struggling with part C of this 3D trig question, I just can't seem to get it out...
Help would be very much appreciated!

Thankyou!!  :)

I will assume the above solution is correct. I am just going to provide tips to doing 3D trigonometry questions.

1. Draw the 3D diagram (or use the given one where applicable), but then draw triangles SEPERATELY
2. Always keep in mind any common sides
3. Label angles where required.

RuiAce

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Re: 3U Maths Question Thread
« Reply #93 on: March 30, 2016, 12:33:02 am »
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Not sure how to get C









Edited on: Also, take note that for the equation y=|x+2|+|x-3| one is able to sketch the corresponding graph by using either:
a) Addition of ordinates
b) Considering the cases seperately like as above.
« Last Edit: March 30, 2016, 10:48:58 am by RuiAce »

RuiAce

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Re: 3U Maths Question Thread
« Reply #94 on: March 30, 2016, 12:38:10 am »
+1
why is it   10C7(1/4)^7(3/4)3           not just (1/4)^7(3/4)3
               C=combination





katherine123

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Re: 3U Maths Question Thread
« Reply #95 on: March 30, 2016, 11:27:36 am »
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Ive attached the question and the answer to part ii
Im not sure why rx=t 

jakesilove

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Re: 3U Maths Question Thread
« Reply #96 on: March 30, 2016, 01:16:01 pm »
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Ive attached the question and the answer to part ii
Im not sure why rx=t

Hey!

Great question, as the explanation isn't great. Basically, it's just an algebraic trick that let's us use the results from part i) in part ii)!

We know that a solution to



is approximately 0.56 from part i). This holds true for any value of t: ie. for any formula e to the power of x equals 1 over x, a rough solution is 0.56. We therefore know that a solution to the equation



also has a solution at



however it may be tough for some students to see exactly why (the fact that this is the same equation as the one in part i)). Therefore, the answers let rx = t to make it visually easier to see why the answer translates.

I hope this makes sense; it's a little profound, but once you've wrapped your head around it it makes sense.

Jake
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katherine123

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Re: 3U Maths Question Thread
« Reply #97 on: March 31, 2016, 06:16:36 am »
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part iii) please thanks

RuiAce

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Re: 3U Maths Question Thread
« Reply #98 on: March 31, 2016, 08:57:58 am »
+1

RussellKindler

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Re: 3U Maths Question Thread
« Reply #99 on: April 01, 2016, 02:33:13 pm »
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Hi could i please have help with this question:
DIfferentiate:


Thanks a lot in advance.

jakesilove

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Re: 3U Maths Question Thread
« Reply #100 on: April 01, 2016, 02:59:07 pm »
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Hi could i please have help with this question:
DIfferentiate:


Thanks a lot in advance.

Hey Russel!

I really hope that I interpreted your question correctly (that it was inverse cos squared, not 2x squared). This was a really tough question, because you need to use so many different rules (Chain, ln, inverse trig etc.). However, I've posted my solution below! Hope it helps :)



Jake
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imtrying

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Re: 3U Maths Question Thread
« Reply #101 on: April 02, 2016, 07:50:47 pm »
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Hey:)
Just wondering if someone could give me a hand with the attached question?
Thank you so much :D
Year 12 2016 (94.20)
English (Adv), Maths Ext.1, Modern History, Biology and Physics

jakesilove

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Re: 3U Maths Question Thread
« Reply #102 on: April 02, 2016, 07:59:04 pm »
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Hey:)
Just wondering if someone could give me a hand with the attached question?
Thank you so much :D

Hey!

For this question, we just need to know the general domain of the inverse sin graph. To know this, either you can recall the graph, test it on a calculator, or memorise the domain!

We know (from one of these methods) that the domain of



is



Therefore, for



We just set



Therefore



is the answer!

Hope this helps :)

Jake
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ATWalk

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Re: 3U Maths Question Thread
« Reply #103 on: April 04, 2016, 11:57:53 am »
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Hey,

Could I please have help on part iii of this question? It's really confusing me. Thanks in advance.

jakesilove

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Re: 3U Maths Question Thread
« Reply #104 on: April 04, 2016, 01:50:17 pm »
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Hey,

Could I please have help on part iii of this question? It's really confusing me. Thanks in advance.

Hey!!

This was actually a crazy projectile motion question: by far the hardest I've ever seen. I don't know if the method I used is the easier, or if it will even make a lot of sense once I've written it out, but it does get to the right answer. I'm sorry I can't be of more help: I'm kind of still reeling from the difficulty of the question! I hope the answer does make sense, but if you'd like me to clarify any specific bit please let me know.




Jake
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