VCE General & Further Maths Question Thread!

[LiquidPaperz]

heres the triangles, do you mind shoing me how they can be flipped etc so they are in same positions

with the spped/ d/t
i use the m = y2 ....

0,0   and    15,6    gets me a gradient of 6/15 = 0.4, not 24?

edit: dw figured out the 24km/hr part didnt see axis had min

[keltingmeith]

heres the triangles, do you mind shoing me how they can be flipped etc so they are in same positions

with the spped/ d/t
i use the m = y2 ....

0,0   and    15,6    gets me a gradient of 6/15 = 0.4, not 24?

edit: dw figured out the 24km/hr part didnt see axis had min

They are similar because the angle BDC is present in both triangles. Then, from the initial information, angle CBD=BAC. So, both triangles have two angles the same, and must be similar. You can get them in the same position by flipping the triangle BCD down (that is, the edge BD in triangle BCD is the same edge as AD in triangle ABD).

For the next question, you've got the wrong units - the gradient of the graph is in km/min, however the question wants the units in km/hour. You need to change the 15 from minutes to hours.

[LiquidPaperz]

thanks euler!

just a question, could you please clarify this again

First line is from the fact that they're similar triangles (I'd need to see the triangles to explain why), the second line is just a cross multiplication of the first line.

thanks

[keltingmeith]

thanks euler!

just a question, could you please clarify this again

thanks

Because the triangles are similar, . Redraw the triangle BCD (after flipping it) next to triangle ABD to see why.

Then, multiply the denominators you, and you get:

[LiquidPaperz]

can someone provide me with the reasons we smooth data? reduce all variation? seasonal only? etcc

[doomdestroyer]

can someone provide me with the reasons we smooth data? reduce all variation? seasonal only? etcc

We smooth data so we can easily see the trends that would otherwise be hidden.

[LiquidPaperz]

can someone give me a constraint for this and tell me why its that.

i originally got 3g is less then or equal to p, this is wrong

[doomdestroyer]

can someone give me a constraint for this and tell me why its that.

i originally got 3g is less then or equal to p, this is wrong

I think you forgot to attach a link as to what you are referring to.

[LiquidPaperz]

yeap sorry!!

[keltingmeith]

yeap sorry!!

So, what we have here is that we don't want some number (x) of the glassware (g) to not exceed some number (y) of the plastic (p). So, our inequality is:

x*g ? y*p

So, the first part is finding x and y. It says in the question that the number of units of g must not exceed 3 times the number of units of p. In a crude sense, this means we have:



Dividing by "number of units", we have g ? 3p

Now, we just need to pick up our inequality from the words. Our gs must not EXCEED the 3ps, so g cannot be greater than 3p. This gives us:



Of course, writing like this is something VCAA doesn't like - so we take the opposite of a strict non-inequality, and get the opposite non-strict inequality.



On opposite symbols:

Strict ----> non-strict (and vice versa)
Less than -----> greater than (and vice versa)

[ETTH96]

Help please!

[Splash-Tackle-Flail]

Could someone help with Q3? I got E, from tan^-1(226/210)

[engton1796]

Got a Multiple Choice question I couldn't figure out.

A regular pentagon, ABCDE, has all sides equal to 8cm.  The length of EC is closest to:  (The triangle is at the top half of the pentagon, thus forming a triangle with 8cm on the left and right upper sides)

A: 13cm
B: 16cm
C: 17cm
D: 22cm
E: 26cm

I got the right answer but later figured out I mistakenly used Pythagoras, so now idk.  Thanks heaps 

[doomdestroyer]

Help please!

Seasonal Index = Value for quarter, so the rainfall in Spring / Quarterly average, so addition of the rainfall for each season divided by four.

[keltingmeith]

Could someone help with Q3? I got E, from tan^-1(226/210)

Angle of depression = angle of elevation (Z-rule), so just find the angle of elevation (it's intuitively easier to find).

However, note that Jill's angle of elevation is the same as Jack's - so, on the off-chance you got the last question wrong, let's use Jill's information:



So, the answer is E.

Got a Multiple Choice question I couldn't figure out.

A regular pentagon, ABCDE, has all sides equal to 8cm.  The length of EC is closest to:  (The triangle is at the top half of the pentagon, thus forming a triangle with 8cm on the left and right upper sides)

A: 13cm
B: 16cm
C: 17cm
D: 22cm
E: 26cm

I got the right answer but later figured out I mistakenly used Pythagoras, so now idk.  Thanks heaps 

We have a regular pentagon with all sides equal - so, all angles must be the same. Since the angles in a pentagon all add up to 540 degrees, we then divide by 5 to find that each angle is 108 degrees.

Now that we know that, we can use the cosine rule (as we have the length of two sides and the angle inbetween). This gives us a length of 12.9 cm, which approximates to A.