VCE Specialist 3/4 Question Thread!

[keltingmeith]

How would you do this question?

P is a point on a circle with centre O. Chord BA is drawn parallel to OP. OA and BP intersect at C.What is the ratio angle of CAB to angle CBA.

Angle at the centre of a circle is twice the angle at the circumference (usually titled circle theorem 1 in textbooks). So,  2DOA=DBA.

D, C and B are collinear, so DBA=CBA.

Using the z-rule, DOA=OAB. Since O, C and A are collinear, OAB=CAB.

From this, we have:
2CAB=2OAB=2DOA=DBA=CBA
Which implies:
2CAB=CBA

So, the ratio of CAB to CBA is 2:1

[knightrider]

Angle at the centre of a circle is twice the angle at the circumference (usually titled circle theorem 1 in textbooks). So,  2DOA=DBA.

D, C and B are collinear, so DBA=CBA.

Using the z-rule, DOA=OAB. Since O, C and A are collinear, OAB=CAB.

From this, we have:
2CAB=2OAB=2DOA=DBA=CBA
Which implies:
2CAB=CBA

So, the ratio of CAB to CBA is 2:1

Thanks EulerFan101 

Where did you get D from though?
also whats z rule ?

[keltingmeith]

Thanks EulerFan101 

Where did you get D from though?
also whats z rule ?

Sorry, D is P LOL. Can't read my own hand-writing. The z-rule is explained here. You've probably seen it before under a different name.

[knightrider]

How would you do this question relating to the image attached?

Given that

AB=BE
AC=AE

Find CD in terms of sin of an angle.

and find AB in terms of sin of an angle.

[knightrider]

How would you do this question relating to the image attached?

Given that

AB=BE
AC=AE

Find CD in terms of sin of an angle.

and find AB in terms of sin of an angle.

Can anyone help with this ?
 

[sprout]

Can anyone help with this ?
 

you basically use the fact that it's an isosceles + sine rule. sorry, might be a bit hard to read bc I used a mouse hahaha

[knightrider]

you basically use the fact that it's an isosceles + sine rule. sorry, might be a bit hard to read bc I used a mouse hahaha

Thankyou so much sprout    really helped !

[Sine]

Do you guys think it's necessary to write notes for spesh or is completing the exercises enough?

[zsteve]

I've always written detailed notes for maths subjects, including worked examples. My viewpoint is here: Maths advice for 2016 graduates-to-be

[lzxnl]

Do you guys think it's necessary to write notes for spesh or is completing the exercises enough?

I taught myself spesh in year 10 just by doing the end-of-chapter exercises in Essentials. As a result, I didn't have to pay attention to spesh in year 12 at all and, well, the rest is history. It really depends on the individual.

[hufflepuff]

How would you do these two questions?

1.'Travelling with constant acceleration, a car passes two posts with velocities v1 and v2 respectively.' Express the velocity of the car when it is halfway between the posts in terms of v1 and v2.'

2.'On a straight road, a car starts from rest with an acceleration of 2m/s^2 and travels until it reaches a velocity of 6m/s, The car then travels with constant velocity for 10 seconds before the brakes causes a deceleration of (v+2)m/s^2 until it comes to rest, where v m/s is the velocity of the car. Find the total distance travelled by the car to the nearest tenth of a second.'

Thanks so much 

[zsteve]

1. Let distance travelled (displacement) be s. Hence, . At the halfway mark, displacement is s/2 so
. From the first equation, rearrange for s and substitute into 2
2. Draw a graph and find the area using geometric means and integration. Your deceleration of (v+2) means so you need to solve a differential equation.
- First segment: calculate distance by
- Second segment - calculate distance as area of rectangle
- Third segment - yeah solve the DE with initial conditions given by the question (i.e. initially v=6) and find the time taken for the car to stop.
A complicated question for kinematics not because it's "hard" but because you need to do so much stuff.
Hope that makes sense

Edit: tex looks so ugly now

[Raj0105]

Could anyone please upload Specialist exam 1 / Math method exam 2 and Chemistry exam paper for 2015.

I have VCE Accounting Exam paper for 2015 , please call me on 0430910990 if you need .

[MightyBeh]

Could anyone please upload Specialist exam 1 / Math method exam 2 and Chemistry exam paper for 2015.

I have VCE Accounting Exam paper for 2015 , please call me on 0430910990 if you need .

They're all already on the forums

Spec Exam 1
Methods Exam 2
Chemistry

[Sine]

What does the dot product of 2 vectors actually signify, I know how go use it to answer q's but I dont feel I understand it fully.

Also I know the derivations for vector resolute formulas but dont know why they work.