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General Forums => The O' Club => Topic started by: Anaxogoras on May 27, 2009, 06:35:16 PM

Title: Trig question help
Post by: Anaxogoras on May 27, 2009, 06:35:16 PM
                                               _
Could there ever be a point (x, - \/3) on a unit circle?  Since r = 1, it would seem to be a contradiction, but a book I'm studying with gives negative square root 3 as a value for the y coordinate.

Here is the problem verbatim:

The ordered pair (x,y) represents a point where the terminal side of angle theta intersects the unit circle... If theta = -(pie/3), what is the value of y.

                       _
My answer is - \/3/2.

-----------------

I'm going back to school in the Fall for a teaching credential and need to retake calculus, so this is my prep-work. :)
Title: Re: Trig question help
Post by: Meatwad on May 27, 2009, 07:39:39 PM
 :huh


The answer is 42
Title: Re: Trig question help
Post by: Serenity on May 27, 2009, 10:33:49 PM
                                               _
Could there ever be a point (x, - \/3) on a unit circle?  Since r = 1, it would seem to be a contradiction, but a book I'm studying with gives negative square root 3 as a value for the y coordinate.

Here is the problem verbatim:

The ordered pair (x,y) represents a point where the terminal side of angle theta intersects the unit circle... If theta = -(pie/3), what is the value of y.

                       _
My answer is - \/3/2.

-----------------

I'm going back to school in the Fall for a teaching credential and need to retake calculus, so this is my prep-work. :)

God I just finished Trig this year and I don't know... wait...  there CAN be a negative radical, but your answer looks wrong... Do you not have a unit circle?

Print out this image, it will save your life in Trig studies.

(http://teacher2.smithtown.k12.ny.us/mrsfisher/images/UnitCircle.gif)

edit: Your answer is exactly right. I missed the negative before the parenthesis pie/3. The tricky part is that while there can be a negative radical 3 over 2, it is NOT at pie over 3, but rather at 4pie over 3. The negative in the initial problem throws it off, but I think your answer is exactly right.
Title: Re: Trig question help
Post by: MORAY37 on May 27, 2009, 10:51:08 PM
                                               _
Could there ever be a point (x, - \/3) on a unit circle?  Since r = 1, it would seem to be a contradiction, but a book I'm studying with gives negative square root 3 as a value for the y coordinate.

Here is the problem verbatim:

The ordered pair (x,y) represents a point where the terminal side of angle theta intersects the unit circle... If theta = -(pie/3), what is the value of y.

                       _
My answer is - \/3/2.

-----------------

I'm going back to school in the Fall for a teaching credential and need to retake calculus, so this is my prep-work. :)

Anax, unit circle will be of great value to you.

Yes, there can and will be a y value of -/3/2, in quadrant 3 and 4.



EDIT: Had posted a unit circle for you, took it down.  Serenity beat me to it.   :salute Serenity
Title: Re: Trig question help
Post by: Serenity on May 27, 2009, 10:55:33 PM
Anax, unit circle will be of great value to you.

Yes, there can and will be a y value of -/3/2, in quadrant 3 and 4.



EDIT: Had posted a unit circle for you, took it down.  Serenity beat me to it.   :salute Serenity

 :salute Moray

Just got out of the subject myself (Literally, today was my very last day!).
Title: Re: Trig question help
Post by: eagl on May 27, 2009, 11:10:40 PM
I use unit circle every day when guesstimating crosswinds, same with 3-4-5 triangles, knowing that a 30/60/90 triangle has one side 1/2 the hypotenuse, etc.  Lots of other pilots wonder why my guesses are always within about 1 knot of actual headwind/crosswind components, and the answer is that I had geometry and trig in high school, early enough that I actually remember some of that stuff.
Title: Re: Trig question help
Post by: MORAY37 on May 27, 2009, 11:18:57 PM
:salute Moray

Just got out of the subject myself (Literally, today was my very last day!).

Trig was so damn bland and repetitive....

The only class I was happier to be rid of then Trig, was Calc. Funny thing is, I absolutely loved both semesters of College Physics.  I didn't really understand most of Calc till I used it in Physics... lol. Although, I took Calculus concurrent with Organic Chem in a semester of 21 credit hours... so that may have been the reason I had issues.

 Thankfully, they don't make biologists take anything higher than Calculus.  I would have never made it.

I do use statistics most every day though, for work.

Title: Re: Trig question help
Post by: Serenity on May 27, 2009, 11:41:36 PM
I use unit circle every day when guesstimating crosswinds, same with 3-4-5 triangles, knowing that a 30/60/90 triangle has one side 1/2 the hypotenuse, etc.  Lots of other pilots wonder why my guesses are always within about 1 knot of actual headwind/crosswind components, and the answer is that I had geometry and trig in high school, early enough that I actually remember some of that stuff.

Any special ideas on how to brush up on the practical geometry pilots use? I honestly don't have a mind for math, and while I had straight As in geometry, I honestly BARELY remember any of it. Hell I got a 590 in Math on my SATs :(
Title: Re: Trig question help
Post by: Anaxogoras on May 28, 2009, 12:59:31 AM
Yes, there can and will be a y value of -/3/2, in quadrant 3 and 4.

Ok, so the book shows the wrong answer, but I still wracked my brains for 20 minutes before I had the courage to believe it. :lol

Thank you for the confirmation.
Title: Re: Trig question help
Post by: Skyeho on May 28, 2009, 01:26:08 AM
God I just finished Trig this year and I don't know... wait...  there CAN be a negative radical, but your answer looks wrong... Do you not have a unit circle?

Print out this image, it will save your life in Trig studies.

(http://teacher2.smithtown.k12.ny.us/mrsfisher/images/UnitCircle.gif)

edit: Your answer is exactly right. I missed the negative before the parenthesis pie/3. The tricky part is that while there can be a negative radical 3 over 2, it is NOT at pie over 3, but rather at 4pie over 3. The negative in the initial problem throws it off, but I think your answer is exactly right.

Also put your tan and cotan on the unit circle.  I found it helped with the "trick" questions my instructor put on the exams.
Title: Re: Trig question help
Post by: Serenity on May 28, 2009, 03:17:32 AM
Also put your tan and cotan on the unit circle.  I found it helped with the "trick" questions my instructor put on the exams.

Ooh! Good idea!
Title: Re: Trig question help
Post by: eagl on May 28, 2009, 08:21:08 AM
Any special ideas on how to brush up on the practical geometry pilots use? I honestly don't have a mind for math, and while I had straight As in geometry, I honestly BARELY remember any of it. Hell I got a 590 in Math on my SATs :(

It's mostly a collection of various rules of thumb.  I don't have them collected in one place, but there might be a civilian book or something out there.

I mostly use unit circle and the 60 to 1 rule.  There are a ton of applications of the 60 to 1 rule, from determining descent rate on an instrument approach to figuring bandit group range and separation on a B-scope radar picture.  Yea, you probably don't know what that means... don't worry about it, if you need it someone will tell you what it means :)
Title: Re: Trig question help
Post by: Serenity on May 28, 2009, 06:10:18 PM
It's mostly a collection of various rules of thumb.  I don't have them collected in one place, but there might be a civilian book or something out there.

I mostly use unit circle and the 60 to 1 rule.  There are a ton of applications of the 60 to 1 rule, from determining descent rate on an instrument approach to figuring bandit group range and separation on a B-scope radar picture.  Yea, you probably don't know what that means... don't worry about it, if you need it someone will tell you what it means :)

Actually, thanks to Falcon 4.0, I sorta understood that!  :D
Title: Re: Trig question help
Post by: Nwbie on May 29, 2009, 09:57:44 AM
I was gonna try and help you out -but then I remembered I played Football in college


 :O

Is that stuff actually taught in school?

:)




Title: Re: Trig question help
Post by: Hoarach on May 29, 2009, 05:37:43 PM
Ha Nwbie it is. 

I just finished my freshmen year of college.

Im a biology/pre-med major and played/playing football.

Its kinda weird that I took Engineering calc 1 and calc 2 (dont know why I did as a biology major, some stupid registration people signed me up for it).  Engineering calc is probably one of the hardest classes to be taken and we used the unit circle maybe 1 or 2 classes and was never seen on a quiz or test.  My school doesn't curve grades and the highest grade in engineering calc was a C+, bad huh lol.
Title: Re: Trig question help
Post by: Fulmar on May 29, 2009, 07:29:11 PM
Its kinda weird that I took Engineering calc 1 and calc 2 (dont know why I did as a biology major, some stupid registration people signed me up for it).  Engineering calc is probably one of the hardest classes to be taken and we used the unit circle maybe 1 or 2 classes and was never seen on a quiz or test.  My school doesn't curve grades and the highest grade in engineering calc was a C+, bad huh lol.

Calc classes help them weed out students who wouldn't be able to crack later courses.  It's not necessarily that you'd use it in your profession to the nth degree you study it, it keeps the dummies out :D
Title: Re: Trig question help
Post by: Anaxogoras on May 29, 2009, 07:34:13 PM
Calc classes help them weed out students who wouldn't be able to crack later courses.  It's not necessarily that you'd use it in your profession to the nth degree you study it, it keeps the dummies out :D

Kind of like the symbolic logic requirement for philosophy.  Don't like it?  Go to the English department where ya belong! :devil

(http://upload.wikimedia.org/math/c/8/b/c8b53eab18990df9e0578dc4d2699b21.png)
 :lol
Title: Re: Trig question help
Post by: Hoarach on May 30, 2009, 12:38:50 AM
Calc classes help them weed out students who wouldn't be able to crack later courses.  It's not necessarily that you'd use it in your profession to the nth degree you study it, it keeps the dummies out :D

I think its funny though that Im the only one in my major that took the course lol.  Calc 1, was a requirement but I could have taken the easier science level calc like the rest of the science majors, no somehow I ended up in the engineer level.  Calc 2 was a complete elective, why I took it no idea.  The joys of college classes.   :lol