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panyan
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Joined: 29 Dec 2007
Posts: 142
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 Posted: 24 May 2009 07:20:24 am Post subject: |
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i have a cheap £6 casio that when i type in sin30, gives me 1/2. Cos 30 gives me rt3/2, etc. How can i get this on my ti 84?
thankyou so much in advance! |
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bfr
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Joined: 13 Feb 2006
Posts: 108
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| Posted: 24 May 2009 10:57:37 am Post subject: |
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Make sure you're in Degree mode, since it seems like that's what you want (press MODE button near the top of the keypad to change the calculator modes).
Last edited by Guest on 24 May 2009 10:58:40 am; edited 1 time in total |
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Weregoose
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Joined: 25 Nov 2004
Posts: 3976
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| Posted: 24 May 2009 10:59:16 am Post subject: |
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You should learn your trig tables!
The patterns are easy to memorize:
[font="courier new"]´´´´´´´´´´´´´´↑
sin(0)´ = cos(90) = √(0)/2
sin(30) = cos(60) = √(1)/2
sin(45) = cos(45) = √(2)/2
sin(60) = cos(30) = √(3)/2
sin(90) = cos(0)´ = √(4)/2
´´´´↓
You can even hammer away at it in case of short-term memory loss:
sin(60
´´´´´.8660254038
Ans[font="verdana"]²
´´´´´´´´´´´´´.75
Ans►Frac
´´´´´´´´´´´´´3/4
Now check to make sure that they are equal:
√(3/4
´´´´´.8660254038
And don't forget about simplifying the square roots!
√(3/4) = √(3) / √(4) = √(3) / 2
In general:
√(m/n) = √(m) / √(n)
Why this mini-lesson? Well, if you understand it well enough to do it on paper, then the calculator ends up wasting your time rather than doing the opposite. 
Last edited by Guest on 11 Jul 2010 05:32:43 pm; edited 1 time in total |
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DigiTan
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| Posted: 24 May 2009 11:12:04 am Post subject: |
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| Getting the right mode has a certain degree of difficulty. |
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panyan
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Joined: 29 Dec 2007
Posts: 142
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| Posted: 24 May 2009 11:38:12 am Post subject: |
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DigiTan wrote: Getting the right mode has a certain degree of difficulty.
im in the right mode (degree), but instead of getting 0.7071 for sin45, i would prefer rt2/2.
Thankyou weregoose, i know the table, i am just worried in the heat of exam i will forget and would like some way of checking via the calculator
Last edited by Guest on 24 May 2009 11:42:18 am; edited 1 time in total |
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DigiTan
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| Posted: 24 May 2009 12:28:07 pm Post subject: |
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Well, if radicals are a bit too radical, it might be worth looking into the Pretty Print or Sybolic v1.8 options. Fair warning: I haven't used these myself, so someone else might want to step in and confirm these are what you're looking for. Or there's oldschool memorization.
Last edited by Guest on 24 May 2009 12:29:15 pm; edited 1 time in total |
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magicdanw
pcGuru()
Calc Guru
Joined: 14 Feb 2007
Posts: 1110
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| Posted: 24 May 2009 01:05:05 pm Post subject: |
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| Symbolic should let you convert the decimal into the radical form. PrettyPrint doesn't do this. |
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panyan
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Joined: 29 Dec 2007
Posts: 142
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| Posted: 24 May 2009 02:01:25 pm Post subject: |
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magicdanw wrote: Symbolic should let you convert the decimal into the radical form. PrettyPrint doesn't do this.
how do i do that? |
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darkstone knight
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Posts: 438
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| Posted: 24 May 2009 03:58:19 pm Post subject: |
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| well, you can try one of the links in DigiTan's post... |
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panyan
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Posts: 142
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| Posted: 24 May 2009 04:08:19 pm Post subject: |
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darkstone knight wrote: well, you can try one of the links in DigiTan's post...
i already have symbolic, i am asking what function of symbolic i am meant to use for the conversion |
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Weregoose
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| Posted: 24 May 2009 05:14:01 pm Post subject: |
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| Are those angles and functions the only ones you're expecting to run into? It would determine the scope of the program that I'm about to create. |
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Weregoose
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| Posted: 25 May 2009 02:13:12 am Post subject: |
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I'd better get this out here before the school week starts.
Press [PRGM] [[font="courier new"]►] [[font="courier new"]►] and select 1:Create New. Name it whatever you want—I'm choosing "TRIG2RAD"—and in the editor, write:
Input X
sub("01√(√(1",4X[font="verdana"]²+1,1
If fPart(2X
Ans+sub("023",4X[font="verdana"]²,1)+")
If fPart(X
Ans+"/2
Ans
Use [2nd] [0] for the CATALOG to get sub(, as well as other commands if you can't locate them in other places.
If you prefer, you can replace Input X in the first line with Ans→X so that the last computation on the home screen always takes on the role of the program's initial input.
Good luck with your exam!
[EDIT] – Changed the 10X to a 2X.
Last edited by Guest on 11 Jul 2010 05:34:12 pm; edited 1 time in total |
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panyan
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Joined: 29 Dec 2007
Posts: 142
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| Posted: 25 May 2009 05:04:15 am Post subject: |
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Weregoose wrote: Input X
sub("01√(√(1",4X[font="verdana"]²+1,1
If fPart(10X
Ans+sub("023",4X[font="verdana"]²,1)+")
If fPart(X
Ans+"/2
Ans
OMG dude! that works so well! i cant believe that works!!! thankyou so much! that is truly awesome!
if only there were a thanks to post button. Also, the problem comes in when i am not allowed programs in the exam, is there a way to hide it like in symbolic where you press math twice?
Last edited by Guest on 11 Jul 2010 05:34:54 pm; edited 1 time in total |
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thornahawk
μολών λαβέ
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Joined: 27 Mar 2005
Posts: 569
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| Posted: 25 May 2009 08:57:04 am Post subject: |
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panyan wrote: the problem comes in when i am not allowed programs in the exam, is there a way to hide it like in symbolic where you press math twice?
Not cool.  If they aren't allowed, then maybe you should be trying to memorize them after all. How hard is it to try to remember five numbers?
thornahawk |
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Eeems
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Joined: 25 Jan 2009
Posts: 277
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| Posted: 25 May 2009 09:43:56 am Post subject: |
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| or you could just remember the program and type it in each time... |
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IAmACalculator
In a state of quasi-hiatus
Know-It-All
Joined: 21 Oct 2005
Posts: 1571
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| Posted: 25 May 2009 11:16:02 am Post subject: |
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| Wow. I just figured out why it said that he was quoting Goose instead of Darkerline. That was quite the fake-out. |
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panyan
Member
Joined: 29 Dec 2007
Posts: 142
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| Posted: 26 May 2009 03:38:52 am Post subject: |
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IAmACalculator wrote: Wow. I just figured out why it said that he was quoting Goose instead of Darkerline. That was quite the fake-out.
i have no idea what you are talking about, back on topic please |
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Weregoose
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| Posted: 26 May 2009 08:06:18 am Post subject: |
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For what it's worth, I made a couple of modifications: the first one appears as an edit in my earlier post, and the second one prepends a negative sign whenever the terminal side is in the third or fourth quadrants. This is the program as it stands now:
Ans→X
sub("01√(√(1",4X[font="verdana"]²+1,1
If X<0
"[font="arial"]-"+Ans
If fPart(2X
Ans+sub("023",4X[font="verdana"]²,1)+")
If fPart(X
Ans+"/2
Ans
Last edited by Guest on 11 Jul 2010 05:36:40 pm; edited 1 time in total |
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Mapar007
Advanced Member
Joined: 04 Oct 2008
Posts: 365
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| Posted: 26 May 2009 01:13:51 pm Post subject: |
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Quote: Also, the problem comes in when i am not allowed programs in the exam, is there a way to hide it like in symbolic where you press math twice?
me=expert in fooling teachers xD
You just install a fake reset app, hide all programs, patch the push-to-test, and your calc is invulnerable.
Fake reset: somewhere on brandonw.net
PTT patch 1: see above
PTT patch 2: http://www.ticalc.org/archives/files/fileinfo/418/41803.html (you'll have to upgrade to OS 2.43 for this one)
Last edited by Guest on 26 May 2009 01:14:47 pm; edited 1 time in total |
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panyan
Member
Joined: 29 Dec 2007
Posts: 142
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| Posted: 26 May 2009 02:32:36 pm Post subject: |
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Weregoose wrote: Ans→X
sub("01√(√(1",4X[font="verdana"]²+1,1
If X<0
"[font="arial"]-"+Ans
If fPart(2X
Ans+sub("023",4X[font="verdana"]²,1)+")
If fPart(X
Ans+"/2
Ans
thankyou for revised code, i have only found one fault (which is by no means a problem), when doing sin(90), the answer is 1, but when using your program it gives it as 1/2.
Also: i have decided that for this exam, i will use the casio as the backup and use it to convert trig to fractions and get back to it after exams
Last edited by Guest on 11 Jul 2010 05:31:17 pm; edited 1 time in total |
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