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  1. J

    Circle Geo Question

    You can use the product of intercepts of intersecting chords theorem. Basically, CE*EF=AE*EB. Since CD bisects AB, AE=EB=7.5. Hence, CE*2=7.5^2 --> CE=7.5^2/2 = 28.125 cm
  2. J

    Done absolutely no work so far these summer holidays?

    Haven't done any work since last year :(
  3. J

    2017ers Chit-Chat Thread

    yeh its most likely acidic environment
  4. J

    Tangents to ellipse

    Another possible method: Since it's parallel to that line, the tangent is in the form of y=-2x/3 + b Now sub this into the equation of the ellipse to get a quadratic in x. Since the line is a tangent, there is only 1 point of intersection, so there are only 1 solution (1 value of x) thus ∆=0. By...
  5. J

    2016ers Chit-Chat Thread

    hsc marks releasing tomorrow right? Well good luck all haha
  6. J

    Parametrics problem

    $\noindent$ $ Normal at P: $x+py=ap^3+2ap \\ $ Normal at Q: $ x+qy=aq^3+2aq. \\$ To find the intersection of these normals, solve them simultaneously. You can subtract them to eliminate $x. \\ \therefore py-qy=ap^3-aq^3+2ap-2aq. \\y(p-q)=a(p^3-q^3)+2a(p-q)$ factorise the difference of cubes...
  7. J

    HSC 2017 MX2 Integration Marathon (archive)

    Re: HSC 4U Integration Marathon 2017 I=\int \frac{(3+4\cos x)}{(4+3\cos x)^2}$ d$x\\ $ Let $t =\tan \left ( \frac{x}{2} \right )\\ $ d$t=\frac{1}{2}\sec^2\left ( \frac{x}{2} \right )$ d$x\\\Rightarrow $ d$x=\frac{2}{1+t^2}$ d$t \\I= 2\int \frac{\left...
  8. J

    2017ers Chit-Chat Thread

    dw cause you're gonna be the dux anyway
  9. J

    Help with projectile motion question?

    Ye for that question, but doesn't have to be true for any other Qs. even if it starts at 0m off the ground, it could end up landing on a 200m cliff. The only time where you can double the time of max height to find the time of flight is when the change in y displacement is 0. ie, the projectile...
  10. J

    Need urgent advice on scholarship/university

    So I was just notified by my school that im eligible for this scholarship from western Sydney university. It's valued at $20000 while also getting a guaranteed entry into WSU and a vip meeting (or something like that idk). The problem is that, I was originally thinking of doing Bachelor of...
  11. J

    Complex Number Help

    For part ii) Turn the mod arg form into x+iy and simplify to get 4z-4=z(1+root3i). Rearrange to get 3z-z√3 i =4. z(3-√3 i)=4. Now make z the subject z=4/(3-√3 i) realising this, we get Z= (4(3+ √3i))/(9+3). Simplify, then Z=(3+root 3i)/3 Typing on phone so soz if it's messy
  12. J

    Question 7 Of Ekman's Compilation

    oh man thats genius
  13. J

    Question 7 Of Ekman's Compilation

    you can write that infinite sum as Im(cisx+cis2x+cis3x+...+cisnx) = Im(cisx+cis^2(x)+cis^3 (x) + ...+ cis^n (x) [DMT]. This is a geometric series, and so you use the formula for the sum of geometric series; Sn=(a(r^n-1)/(r-1)). They have basically written that in terms of t. So both the common...
  14. J

    help with locus ?!?!?

    If you simultaneously try to solve the equation of the parabola and chord of contact equation, (note that a=1) then you'll end up with a quadratic in x. The roots of this quadratics are the x coordinate of M and Q. So to find the midpoint of it, youll do (x1+x2)/2= sum of roots/2. Now the sum of...
  15. J

    HSC 2017 MX2 Integration Marathon (archive)

    Re: HSC 4U Integration Marathon 2017 started ages ago, from watching vids and looking at other peoples working out on marathons. (thats partially how i grasped integration by substitution lol, by looking at people making dx the subject etc). Then participating in marathons strengthens the...
  16. J

    HSC 2017 MX2 Integration Marathon (archive)

    Re: HSC 4U Integration Marathon 2017 lmao no way, I shouldn't be even compared to him
  17. J

    HSC 2017 MX2 Integration Marathon (archive)

    Re: HSC 4U Integration Marathon 2017 $\noindent$I= \int \frac{1-a^2}{1-2a \cos x + a^2}$ d$x \\ = (1-a^2)\int\frac{1}{1+a^2-2a(2\cos^2(\frac{x}{2})-1)} $ d$x \\(1-a^2) \int \frac{1}{(1+a)^2-4a \cos^2 \frac{x}{2}}$ d$x\\\\ $Let $t=\tan \frac{x}{2}\Rightarrow $ d$t=\frac{1}{2}\sec...
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