having major trouble with TRIG

[dent1011]

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hey everyone

my dats in a few days and im really struggling with trig 🙁

ive read the sections about it in kaplan and barrons but it doesnt help me when tryin to solve problems... i also looked on the internet but it is very overwhelming

i do not know how to approach problems and apply the trig functions...!
can somebody please help me

what is crucial to memorize / know?
how much trig appears on the QR


for example i dont know how to answer these... (attached)

any help or resources would be greatly appreciated!! 🙂

 

[militantmango]

I was having major trouble with trig too, until I took the time to memorize the unit circle (which I had totally forgotten post-high school). Look up the unit circle on Wikipedia...there is a good picture of it...

I would say it's important to know:

- What sin/cos/tan equal at certain degrees/radians (for example, sin(30 degrees) = 1/2)
- When sin/cos/tan are negative (i.e. in which quadrants)
- That cscx = 1/sinx, secx = 1/cosx, and cotx = 1/tanx
- That sin(^2)x + cos(^2)x = 1
- That sin(2x) = 2sinxcosx

I hope this helps! Just memorize and practice with all of that and you should do fine. As for the problem you listed, I think the answer is C, 17:

Since siny = 1/cscy...
sin(3x - 26) = 1/csc(5x - 60)
3x - 26 = 5x - 60 (y=y)
Solve for x and you get 17...

Anyone else get this?

 

[casper22]

Me too got 17 for the first prob..

How about the second one... i reached a point where I have cos^2x = -3....

but 3 is nowhere in the answer choice... meaning I am not doing it correctly..

I started with substituting 1 as cosec^2x - cot^2x....

Anybody...

 

[militantmango]

Uh...I'm kinda at a loss...

4csc(^2)x - 1 = 0
4csc(^2)x = 1
csc(^2)x = 1/4 (Square root both sides...)
cscx = 1/2
sinx = 2...but sinx never equals 2 between 0 and 360 degrees...
So I'm tempted to say E...

Am I just being an idiot here?

 

[nyr201]

i too am having trouble with trig...does anyone know how many trig problems we can expect to see on average on a QR section?

if its 1-2 questions then i will just wing it with SOH CAH TOA lol.

the reason why im thinking of winging it is bc i have a week left til my exam and i need to better organize my time and spend time on things with more value...thanks in advance

 

[TK2006]

Uh...I'm kinda at a loss...

4csc(^2)x - 1 = 0
4csc(^2)x = 1
csc(^2)x = 1/4 (Square root both sides...)
cscx = 1/2
sinx = 2...but sinx never equals 2 between 0 and 360 degrees...
So I'm tempted to say E...

Am I just being an idiot here?

First is 17.

Second is {empty}.

Your work for the second one is entirely correct. I remember seeing this problem on TopScore, btw.

 

[militantmango]

Wooo! I'm glad I got that right lol! =)

 

[TK2006]

Wooo! I'm glad I got that right lol! =)

Good luck on your test tomorrow. You seem like you got this! 😀

 

[dent1011]

Thanks guys
but i do not understand why in the 2nd problem:

" sinx = 2...but sinx never equals 2 between 0 and 360 degrees... "

can somebody please explain

thank youuu !!

 

[Pat Kelly]

Thanks guys
but i do not understand why in the 2nd problem:

" sinx = 2...but sinx never equals 2 between 0 and 360 degrees... "

can somebody please explain

thank youuu !!

the highest values for sinx = 1, it's a periodic function that oscillates between 1 and -1, so there shouldn't be an answer - you can look at a sine or cos graph for this since cosine graph is just a sine graph displaced horizontally by pi/2

 

[flower123]

I had a quick question on the second one...can they it not be A?
csc(^2)x = 1/4
cscx = 1/2 (can this be +/- 1/2) or I am just getting confused? (because when we square 1/2 or -1/2 we get 1/4 both times.

 

[flower123]

I had a quick question on the second one...can they it not be A?
csc(^2)x = 1/4
cscx = 1/2 (can this be +/- 1/2) or I am just getting confused? (because when we square 1/2 or -1/2 we get 1/4 both times.

 

[mashinka]

http://forums.studentdoctor.net/showthread.php?t=658017

look at the thing this guy posted. Its amazing and after I learned it, every trig functions seems like cake.