Discussion and Suggested Solutions - Mathematics 2017

[Anything]

Hey Jamon, with the dL/dx = 0 question, you could have subbed in sin(alpha) and sin(beta), using the trig identity (right angled triangle). Albeit maintaining the factorised form
(as a shorter method)

[con_fisher]

Hey, for 16.a)ii) You were meant to differentiate, which gave you the trigonometric values of the triangle. You were not meant to solve for x yet. e.g. sin(alpha) = x/root(25+x^2) and sin(beta) = (9-x)/root(49+(9-x)^2 which gives you 0 = sin(alpha) - sin (beta), so sin(alpha) = sin(beta)

[Rosie52273]

you forgot the pii in 12 b

[inescelic]

For 16ci, did anyone else use "line joining the midpoints of two sides of a triangle is parallel to and equal to half of the third side?" i didn't need to prove similarity and im worried that my proof isn't valid as a result???
D;

I did the same thing... like transversals on parallel lines are in the same ratio?

[herb123]

how did u find the exam Jamon?!. In comparison to previous years

[jamonwindeyer]

For 16ci, did anyone else use "line joining the midpoints of two sides of a triangle is parallel to and equal to half of the third side?" i didn't need to prove similarity and im worried that my proof isn't valid as a result???
D;

I don't think that's a quotable result unfortunately

Hey, for 16.a)ii) You were meant to differentiate, which gave you the trigonometric values of the triangle. You were not meant to solve for x yet. e.g. sin(alpha) = x/root(25+x^2) and sin(beta) = (9-x)/root(49+(9-x)^2 which gives you 0 = sin(alpha) - sin (beta), so sin(alpha) = sin(beta)

Hey Jamon, with the dL/dx = 0 question, you could have subbed in sin(alpha) and sin(beta), using the trig identity (right angled triangle). Albeit maintaining the factorised form
(as a shorter method)

Ahh, clever! I just jumped straight into the brute force since I was in a rush

My method would definitely still be worth full marks, but definitely isn't as efficient as you guys, good stuff on spotting it!!

you forgot the pii in 12 b

Welcome to the forums! That should be fixed now if you look again

I did the same thing... like transversals on parallel lines are in the same ratio?

That is a quotable result

[navtejkr]

I dont understand how with the last multiple choice question , the direction changes only once? i thought it was 3 times ?

[con_fisher]

Hey, in this do we have to specify that a =/= 2 ? Because if r = 0 then a = 2, but do we have to specify that r =/= 0 ? Thank you

[goodguy]

For the 2 significant figures question shouldn't the answer be 870, considering you use the proper k value? not the approximation, also last question of 11 shouldn't the range be cut off to root 3

[portia1605]

what do you think you would need for a state rank? 99?

[FirKangaroo]

Hey guys, I'm new to the forum. Where is everyone getting the solutions to the 2u exam? Could anyone link me please ?

[ang3244]

I did the same thing... like transversals on parallel lines are in the same ratio?

I'm worried because my proof was literally:
In triangle BEC:
D bisects BE (line [MD] joining midpoints of two sides [BE and MC] is parallel to and equal to half the length of the third side [CE])
∴ BD = DE
∴ DE = DA + AC
and since DE = DA + AE as well,
AC = AE ∴ isoceles triangle
And I don't know if the midpoint thing was a correct assumption (like got the answer but will I lose marks for working)?

[Anything]

I dont understand how with the last multiple choice question , the direction changes only once? i thought it was 3 times ?

The question illustrated a velocity graph and we know direction changes when the sign of velocity changes from positive to negative or negative to positive, since the graph crossed the x axis, only once it changed direction only once.

[banway]

Hey guys, I'm new to the forum. Where is everyone getting the solutions to the 2u exam? Could anyone link me please ?

Jump back to page one and there are expandable spoilers


Also just wondering, I'm probably being a bit paranoid, but how much do they care about the setting out of the working? I'm worried mine might have been too crammed onto the pages even where I spilled into another book. As long as I've underlined all the answers and my writing is legible I should be ok yeah? Also is on the smaller side handwriting still alright cus my writing isn't huge scrawl, like half of the 10mm lines they give so like 5mm 

[mbdtHSC]

What do you think 95 raw would become