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 deXtrous
complete tool
Registered: 04/24/06
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 How do I do trigonometry without a calculator? 
#10030809 - 03/24/09 01:40 AM (15 years, 27 days ago) |
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Hey folks, I have a test coming up to join the Defence Force but you are not allowed to use a calculator and I hear there are some basic questions for trig. I've always done it with a calculator which was piss easy but you are not allowed to use one in the test. How would I, say, find out the angle or side of a triangle using the COS SIN and TAN methods in trigonometry?
Thank you.
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 SlashOZ
:D
Registered: 10/20/06
Posts: 3,557
Loc: Following the water cycle
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Re: How do I do trigonometry without a calculator? [Re: deXtrous]
#10030817 - 03/24/09 01:42 AM (15 years, 27 days ago) |
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The Defense Force? Sounds like the military. If it is the military then expect to become a grunt if you can't answer trig questions without a calculator. Which is fine cuz you live in Australia and lets face it, your country is pretty chill with everyone.
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"Life sucks but in this really beautiful way" - Axl Rose
"Life's a bitch and then you die that's why we get high cuz you never know when you're gonna go." - NAS
"When people don't know what you're about they put you down and shut you out" - Black Sabbath
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"Don't question my reality." - Me (as far as I know)
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suburbanned
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Re: How do I do trigonometry without a calculator? [Re: SlashOZ]
#10030831 - 03/24/09 01:48 AM (15 years, 27 days ago) |
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soh cah toa
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Chubba
Vape hungry
Registered: 07/05/07
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Re: How do I do trigonometry without a calculator? [Re: deXtrous]
#10030833 - 03/24/09 01:48 AM (15 years, 27 days ago) |
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Fellow Aussie.
I've done practically all the tests for the Army, general entry and officer. I didn't end up joining because I wasn't offered a pilot position.
If it's general entry, you can easily brush up on the material within 3-5 hours (read: within a week unless you're a complete slack ass).
Combination of google and wikipedia with the right choice of words and you will be good to go, it's quite simple. No need to buy any texts, just websites, high school trig exams etc. and a bit of reference for the occasion formula.
If you got a really good head on your shoulders, you can do grade 8 - 10 trig within 60 minutes.
BTW what are you applying for?
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Entropymancer
Registered: 07/16/05
Posts: 10,207
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Re: How do I do trigonometry without a calculator? [Re: SlashOZ]
#10030836 - 03/24/09 01:48 AM (15 years, 27 days ago) |
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a/sin(A) = b/sin(B) = c/sin(C), ennit?
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suburbanned
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Re: How do I do trigonometry without a calculator? [Re: Entropymancer]
#10030843 - 03/24/09 01:52 AM (15 years, 27 days ago) |
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yes it is but he sated he can't use a calculator
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deXtrous
complete tool
Registered: 04/24/06
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Loc: Australia
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Re: How do I do trigonometry without a calculator? [Re: Entropymancer]
#10030850 - 03/24/09 01:54 AM (15 years, 27 days ago) |
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Quote:
Entropymancer said:
a/sin(A) = b/sin(B) = c/sin(C), ennit?
oh yes.. it's starting to come back to me now... kinda
Take this question for instance, who can solve it with the steps involved for me please?
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Coaster
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Re: How do I do trigonometry without a calculator? [Re: deXtrous]
#10030862 - 03/24/09 01:57 AM (15 years, 27 days ago) |
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unless thats a right triangle there isn't sufficient information to find EC
assuming it is u use the four thousand year old pythagorean theorem
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deXtrous
complete tool
Registered: 04/24/06
Posts: 1,743
Loc: Australia
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Re: How do I do trigonometry without a calculator? [Re: Coaster]
#10030865 - 03/24/09 01:59 AM (15 years, 27 days ago) |
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it definitely is a right angled triangle.. Ah Pythagoras theorem, there's a word I should have rememebered!
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blewmeanie
Registered: 10/01/06
Posts: 28,984
Loc: 
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Re: How do I do trigonometry without a calculator? [Re: deXtrous]
#10030868 - 03/24/09 02:01 AM (15 years, 27 days ago) |
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If its a right triangle then ec = the square root of ed2 + dc2
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Coaster
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Re: How do I do trigonometry without a calculator? [Re: deXtrous]
#10030869 - 03/24/09 02:01 AM (15 years, 27 days ago) |
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well whoever made that problem is fucked up because you always have to indicate right angles...
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blewmeanie
Registered: 10/01/06
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Re: How do I do trigonometry without a calculator? [Re: Coaster]
#10030872 - 03/24/09 02:03 AM (15 years, 27 days ago) |
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Chubba
Vape hungry
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Re: How do I do trigonometry without a calculator? [Re: Coaster]
#10030874 - 03/24/09 02:03 AM (15 years, 27 days ago) |
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Quote:
well whoever made that problem is fucked up because you always have to indicate right angles...
+1
It's not a right angle until it's indicated no matter how perfectly drawn.
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Coaster
Baʿal
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Re: How do I do trigonometry without a calculator? [Re: Chubba]
#10030879 - 03/24/09 02:04 AM (15 years, 27 days ago) |
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ya if i gave that problem to my geometry students they would tell me that it looks like a right angle yet could possible be 89.999 degrees making your answer not exact
and not exact is fail
your answer would be slightly smaller than the real answer
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SlashOZ
:D
Registered: 10/20/06
Posts: 3,557
Loc: Following the water cycle
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Re: How do I do trigonometry without a calculator? [Re: deXtrous]
#10030897 - 03/24/09 02:12 AM (15 years, 27 days ago) |
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Quote:
deXtrous said:
Quote:
Entropymancer said:
a/sin(A) = b/sin(B) = c/sin(C), ennit?
oh yes.. it's starting to come back to me now... kinda
Take this question for instance, who can solve it with the steps involved for me please?
Take 'a' squared plus 'b' squared equals 'c' squared.
So when you plug in the numbers it is:
8 squared = 64
6 squared = 36
36+64=100
Where then 100 comes to symbolize 'c' squared.
To find the solution you need to figure out what number multiplied with itself is equal to 100.
The square root of 100 is 10.
Therefore the length of the missing side is 10.
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"Life sucks but in this really beautiful way" - Axl Rose
"Life's a bitch and then you die that's why we get high cuz you never know when you're gonna go." - NAS
"When people don't know what you're about they put you down and shut you out" - Black Sabbath
"An eye for an eye makes the whole world blind" - Gandhi
"Look up at me I am God, look down on me and I am evil, look at me I am you." - Charles Manson.
"Don't question my reality." - Me (as far as I know)
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deXtrous
complete tool
Registered: 04/24/06
Posts: 1,743
Loc: Australia
Last seen: 1 year, 19 days
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Re: How do I do trigonometry without a calculator? [Re: deXtrous]
#10030899 - 03/24/09 02:13 AM (15 years, 27 days ago) |
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Yes right well I took the answer out of context as it was originally as rectangle I just erased it to make it simpler in MS paint. Anyway, How would I go about finding an angle in a triangle rather than the side? Something like entropymancer said "a/sin(A) = b/sin(B) = c/sin(C)" but that doesn't seem right ?
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Astral soul
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Re: How do I do trigonometry without a calculator? [Re: Coaster]
#10030932 - 03/24/09 02:29 AM (15 years, 27 days ago) |
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sine rule is: a/sinA = b/sinB = c/sinC
cosine rule is: a2 = b2 + c2 − 2bc cos A
Which rule you use depends whether you know two angles and a side or two sides and an angle. You can resolve all the angles and sides using these formula.
I cant see you will be asked to do this without a calculator unless they supply you with the old fashioned tables to read sin and cosine values from. Perhaps they will ask you to find the unkown length of a right angle triangle by multiplying a known length by the tangent of the known angle?
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Edited by Astral soul (03/24/09 02:32 AM)
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blewmeanie
Registered: 10/01/06
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Re: How do I do trigonometry without a calculator? [Re: deXtrous]
#10030933 - 03/24/09 02:29 AM (15 years, 27 days ago) |
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Rainman420
Music is my Life
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Re: How do I do trigonometry without a calculator? [Re: deXtrous]
#10030939 - 03/24/09 02:31 AM (15 years, 27 days ago) |
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yeah entropymancer is right.
You have to have an angle or theta to be able to calculate it. If you have an angle, then you can use the Law of Sines. "a/sin(A) = b/sin(B) = c/sin(C)"
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From abundance to selfishness;
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Prisoner#1
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Re: How do I do trigonometry without a calculator? [Re: SlashOZ]
#10031121 - 03/24/09 04:52 AM (15 years, 27 days ago) |
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Quote:
SlashOZ said:
The Defense Force? Sounds like the military. If it is the military then expect to become a grunt if you can't answer trig questions without a calculator. Which is fine cuz you live in Australia and lets face it, your country is pretty chill with everyone.
australia had troops in iraq and afghanistan, I dont think they're too thrilled about it
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