VCE General & Further Maths Question Thread!

[Zealous]

Hey Frank, did you do geometry and trigonometry module? How did you find the SAC?

I did Geometry and Trigonometry.

Just draw diagrams for everything! I lost some stupid marks on my SAC because I thought Cathy was looking towards the right of a watchtower with an angle of depression rather than towards the left. If I drew a diagram I would've realised that the particular situation was impossible.

[dankfrank420]

What strategy do you guys use for those linear programming questions where the corner is continuous (eg. 10.2) but only integer solutions are accepted?

[_fruitcake_]

What strategy do you guys use for those linear programming questions where the corner is continuous (eg. 10.2) but only integer solutions are accepted?

integer numbers inside the area allowed- any numbers inside there. Time consuming but not many questions like these appears

[dankfrank420]

integer numbers inside the area allowed- any numbers inside there. Time consuming but not many questions like these appears

Yeah, going through past VCAA questions I couldn't find any.

But my teacher said I need to learn how to do this so I think it will be on the SAC coming up.

[_fruitcake_]

Yeah, going through past VCAA questions I couldn't find any.

But my teacher said I need to learn how to do this so I think it will be on the SAC coming up.

Teacher said the same thing. I have done the textbook already and i am pretty positive its not on there. Yeah its worth looking at it if our teachers say its important.

In the unlikely event that it appears on the exam then you are in a great position

[Peanut Butter]

How do you know when to use a point IN the feasible region and when to use a feasible region vertex?

Or should you never assume it is a corner?

[_fruitcake_]

How do you know when to use a point IN the feasible region and when to use a feasible region vertex?

Or should you never assume it is a corner?

A corner is in the feasible region if the equations that make the feasible region are greater/less than or EQUAL to. That means you can use a corner. Its always the corner except for the content of the question. For example if the maximun profit made is in the corner (10.56,7.89) and the question is asking for how many tables to sell, you cant sell a 10.56 of a table. So then you have to look inside the feasible region for solid numbers to adjust yourself to the context of the question.

[StupidProdigy]

The answer to this is 1:9, however I had 1:27. The solutions said the scale factor had to be squared rather then cube because the length wasn't changing as the cross-sectional area did or something like that..I can't really follow what they mean...any help would be appreciated thanks!

[plato]

The answer to this is 1:9, however I had 1:27. The solutions said the scale factor had to be squared rather then cube because the length wasn't changing as the cross-sectional area did or something like that..I can't really follow what they mean...any help would be appreciated thanks!

Let's simplify the question by considering a cube with side length L. The volume is LxLxL =L³
If we triple the length of only one side, the volume is now LxLx3L=3L³ . This is only triple the original volume.
If we were to triple two of the sides of the original box, the volume is then Lx3Lx3L = 9L³ or 3²L³
Only when we triple all three of the original sides will be get 3Lx3Lx3L = 27L³ which is 3³ times the original volume

In summary - tripling only one dimension (ie L ot W or H) will multiply the original volume by 3 - ie only multiply by one scale factor
Tripling two dimensions only will multiply the original volume by 3² - ie square the scale factor
Tripling all three dimensions will multiply the original volume by 3³ - ie cube the scale factor

Similarly if you were to multiply any two dimensions by 7, the volume will increase by a factor of 7² or 49

In your example, the ratio of the height of water:height of gauge = 1:3 or 1/3 as a fraction. This would also mean that the distance across the surface of the water to the sloping edge:similar distance across the top of the guage is also 1:3 or 1/3 as a fraction. But the width of the rain guage (between paralell triangular faces) has not changed. So only two dimensions are different and so we only square two ratios as in (1/3)² = 1/9 or 1:9

[@#035;3]

Hey guys quick question, thanks in advance

The bearing of a ship,S from lighthouse,A, is 055 Degrees. A second lighthouse, B is due east of A. The bearing of S from B is 302 degrees. Find the magnitude of angle ASB.

[MightyBeh]

Hey guys quick question, thanks in advance

The bearing of a ship,S from lighthouse,A, is 055 Degrees. A second lighthouse, B is due east of A. The bearing of S from B is 302 degrees. Find the magnitude of angle ASB.

1. First step for a question like this is a diagram; my one's down below, but it's relatively simple as long you draw the compass markers along with each point.

^{obviously not to scale} 

2. Secondly, we need to find out the interior angles of our triangle so we can use the 180° rule to find the magnitude of ASB, or if you prefer the angle of S.

So to find the angle SAB, or the angle A, we us do this:


Where the 90 is used because the angle occupies solely the first quadrant. (if you need it, I can hook you up with a diagram for this, I'm a little ashamed it took me longer than it should to work that out  )

We still don't have enough information to work out ASB, so let's work out SBA. It's not super obvious from my diagram, but the point S is in the fourth quadrant of B's compass so we do this to work out the magnitude:



So now we have the angles 35, 32 and x in our triangle. A quick bt of algebra or solve() should knock this right out:




And there (hopefully) is our answer: The magnitude of the angle ASB is 113°

[MorgnD]

http://imgur.com/KmfyjLT
Can someone explain why E is the answer for this question?

[Floatzel98]

Key word here is vertical. Some of those answers are just straight line graphs. One is a hyperbola and one is a horizontal line.

[MorgnD]

Key word here is vertical. Some of those answers are just straight line graphs. One is a hyperbola and one is a horizontal line.

Ahhh thank you

[BakedDwarf]

If a critical path goes through a dummy activity, do we include the dummy activity as part of the critical path?

For example, is the critical path B-G-J-M-N
                                                           or
                                             B-dummy-G-J-M-N