Prelim 2016 Maths Help Thread (2 Viewers)

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InteGrand

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for the question;
let t=tan(θ/2), solve for the equation 12tan(θ)=5 for 180<θ<270
I got the answers as t=1/5 or t=-5 but the answer given by the textbook is only -5..why?
Since we are only interested in 180° < θ < 270°, clearly 90° < θ/2 < 135°, so tan(θ/2) (i.e. t) has to be negative (since θ/2 is in the second quadrant).

(And of course, that equation very easy to solve without t-method.)
 

Green Yoda

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Since we are only interested in 180° < θ < 270°, clearly 90° < θ/2 < 135°, so tan(θ/2) (i.e. t) has to be negative (since θ/2 is in the second quadrant).

(And of course, that equation very easy to solve without t-method.)
ahh ok
 

eyeseeyou

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How do I do the following:

1. If tan(theta)=t, express cos (squared) (theta) in terms of t
2.a. Given n x=2/3, find the possible value of cosx and cosecx
b. Given sinA=-0.6, find the psooible value of secA and tanA
c. If cot(theta)=-40/9 and 270<(theta)<360 find sin (theta) and cos (theta)
d. If sinb=s, express cosb and tanb in terms of s
e. If x is acute and sinx=1/(squareroot 5) show that tanx/1-secx = -2-(squareroot of 5). Find the value of this fraction when x is obtuse
f. If 5tanx=2, find the value of 5cosx-2sinx/cosx
 

leehuan

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For some questions you should really use more brackets. (Also this post will be edited - I'll do a few more)
_______



Do the same for sec, noting that cosine is positive in the fourth quadrant or negative in the third. Note that secant is then hypotenuse/adjacent
_______


_______

Then just use tan=sin/cos
 
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leehuan

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Oh yeah shit

For which questions?
Just fix up any brackets to questions I didn't attempt. I just didn't want to trial and error.

If no brackets are necessary at all to distinguish between fractions and etc then leave untouched.
 

eyeseeyou

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Need help (leehuan or Integrand). I seem to be confused with this shit for some reason

1. \frac{2x+1}{x}<1
2. \frac{x}{2x+3}\leq5
3. \frac{-1}{t-1}\leqt
4. \frac{10t+1}{4t-1}\leq t+1
5. \frac{t-1}{t+1}<t
6. 3t-2\leq \frac{6t}{t+1}

Fucking hell it took me too long
 

eyeseeyou

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Need help (leehuan or Integrand). I seem to be confused with this shit for some reason

1. \frac{2x+1}{x}<1
2. \frac{x}{2x+3}\leq5
3. \frac{-1}{t-1}\leqt
4. \frac{10t+1}{4t-1}\leq t+1
5. \frac{t-1}{t+1}<t
6. 3t-2\leq \frac{6t}{t+1}

Fucking hell it took me too long
wtf happened leehuan/integrand help me fix it up
 

InteGrand

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wtf happened leehuan/integrand help me fix it up


Type [tex.] [/tex.] (without the full stops). Then place your codes inside those. Also, it's good to leave spaces between things, like put a space between \leq and 5 for example, otherwise the code can mess up here sometimes.
 

leehuan

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Need help (leehuan or Integrand). I seem to be confused with this shit for some reason

1. \frac{2x+1}{x}<1
2. \frac{x}{2x+3}\leq5
3. \frac{-1}{t-1}\leqt
4. \frac{10t+1}{4t-1}\leq t+1
5. \frac{t-1}{t+1}<t
6. 3t-2\leq \frac{6t}{t+1}

Fucking hell it took me too long
Lol yeah you have to wrap your latex around the
 

Nailgun

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Yeah I tried that but then I ended up fcking the answers

Wait...how do I do that?
multiply both sides by the square of the denominator to get rid of it
it should be trivial to solve then
 
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