Edexcel A2 C4 Mathematics June 2016 - Official Thread

What is meant by produced in vector geometry?

For example: The line

{\vec{OE}}

produced meets the line

AB

at

F

Reply 1101

crashMATHS

16

Original post by NotNotBatman

What is meant by produced in vector geometry?

For example: The line

{\vec{OE}}

produced meets the line

AB

at

F

From what it seems, I guess it means if you extended (produced) the line OE it would meet the line AB at the point F

Reply 1102

cookiemonster15

17

Quick Question: For question number two on this paper

https://5c59854d0ccd29d489c9e5e689a8bbadf49aa0f0.googledrive.com/host/0B1ZiqBksUHNYREhxMHhfam1IQm8/for-Edexcel/Solomon%20C%20QP%20-%20C4%20Edexcel.pdf

How do you know whether to use radians or degrees? I went ahead to use degrees however the mark scheme was in radians? Any help?

:smile:

Reply 1103

joodaa

5

Original post by cookiemonster15

Quick Question: For question number two on this paper

https://5c59854d0ccd29d489c9e5e689a8bbadf49aa0f0.googledrive.com/host/0B1ZiqBksUHNYREhxMHhfam1IQm8/for-Edexcel/Solomon%20C%20QP%20-%20C4%20Edexcel.pdf

How do you know whether to use radians or degrees? I went ahead to use degrees however the mark scheme was in radians? Any help?

:smile:

Trig can only be integrated if it's in radians I think

Reply 1104

cookiemonster15

17

Original post by joodaa

Trig can only be integrated if it's in radians I think

Ah ok, didn't know that. :smile:

Reply 1105

Zacken

22

Original post by joodaa

Trig can only be integrated if it's in radians I think

Original post by cookiemonster15

Ah ok, didn't know that. :smile:

You can only integrate/differentiate trigonometric functions if it is in radians. Basically, all calculus is in radians.

(NB: you could do it in degrees but you'd need the scaling factors and the taylor series gets all ****ed up, so let's not)

Reply 1106

Serine Soul

18

Original post by aymanzayedmannan

This is what I got :biggrin:

Spoiler

@Zacken I tried yours but kept going round in circles so I gave up and went to sleep (well watched a horror move but that's a different story)

Reply 1107

tiny hobbit

15

Original post by NotNotBatman

What is meant by produced in vector geometry?

For example: The line

{\vec{OE}}

produced meets the line

AB

at

F

Original post by kingaaran

From what it seems, I guess it means if you extended (produced) the line OE it would meet the line AB at the point F

Yes but you must extend it past E. If you wanted to go past O it would be described as EO produced.

An old fashioned word, but very useful.

Reply 1108

Mihael_Keehl

15

Please can someone explain to me Question 8d from Ex5B

How is BG = 3b? Should it not be equal to 2b?

https://e1934e482e1b0d2c8580c3a986eb005fbbe9e596.googledrive.com/host/0B1ZiqBksUHNYcHVKUE1IOEZ3UTQ/CH5.pdf

Page 20-21. THnak,s

Reply 1109

tiny hobbit

15

Original post by cookiemonster15

Quick Question: For question number two on this paper

https://5c59854d0ccd29d489c9e5e689a8bbadf49aa0f0.googledrive.com/host/0B1ZiqBksUHNYREhxMHhfam1IQm8/for-Edexcel/Solomon%20C%20QP%20-%20C4%20Edexcel.pdf

How do you know whether to use radians or degrees? I went ahead to use degrees however the mark scheme was in radians? Any help?

:smile:

Original post by Zacken

You can only integrate/differentiate trigonometric functions if it is in radians. Basically, all calculus is in radians.

(NB: you could do it in degrees but you'd need the scaling factors and the taylor series gets all ****ed up, so let's not)

I think that it is particularly unkind when this turns up in C2 when you haven't started differentiating or integrating trig functions.

Reply 1110

tiny hobbit

15

Original post by Mihael_Keehl

Please can someone explain to me Question 8d from Ex5B

How is BG = 3b? Should it not be equal to 2b?

https://e1934e482e1b0d2c8580c3a986eb005fbbe9e596.googledrive.com/host/0B1ZiqBksUHNYcHVKUE1IOEZ3UTQ/CH5.pdf

Page 20-21. THnak,s

Their solution says 2b????

Reply 1111

Zacken

22

Original post by Mihael_Keehl

Please can someone explain to me Question 8d from Ex5B

How is BG = 3b? Should it not be equal to 2b?

https://e1934e482e1b0d2c8580c3a986eb005fbbe9e596.googledrive.com/host/0B1ZiqBksUHNYcHVKUE1IOEZ3UTQ/CH5.pdf

Page 20-21. THnak,s

The PDF clearly says

\vec{BG} = 2b

where are you seeing 3b from?

Edit: ninja-ed.

Reply 1112

bat_man

2

Can someone please help me with connected rates of change. They get me every time. Question 9 of exercise 4E from the heinemann c4 textbook, pls.

Reply 1113

ULTRALIGHT BEAM

2

What topics in C4 do you find the simplest and hardest?

For me TR is by far the easiest. Beyone the fact it's merely adding numbers together, but you can check the answer on your calculator. Also the follow up Q to most TR Qs are integrating the function anyway..

I find vectors quite weird, especially the Qs where it's about finding the shortest distance or something like that..

Reply 1114

ULTRALIGHT BEAM

2

Original post by bat_man

Can someone please help me with connected rates of change. They get me every time. Question 9 of exercise 4E from the heinemann c4 textbook, pls.

Post the Q

Reply 1115

bat_man

2

Original post by ULTRALIGHT BEAM

Post the Q

Fluid flows out of a cylindrical tank with constant cross section. At time t minutes, t>0, the volume of fluid remaining in the thank is Vm^3. The rate at which the fluid flows in M^3min^-1 is proportional to the sq root of V.
Show that the depth h metres of fluid in the tank satisfies the differential equation
dh/dt = -k root h, where k is a positive constant.

Reply 1116

ULTRALIGHT BEAM

2

Original post by bat_man

Fluid flows out of a cylindrical tank with constant cross section. At time t minutes, t>0, the volume of fluid remaining in the thank is Vm^3. The rate at which the fluid flows in M^3min^-1 is proportional to the sq root of V.
Show that the depth h metres of fluid in the tank satisfies the differential equation
dh/dt = -k root h, where k is a positive constant.

Zacken is really good at explaining. Can't understand the Q

NB: dh/dt = dvdh / dtdv

Reply 1117

bat_man

2

Original post by ULTRALIGHT BEAM

Zacken is really good at explaining. Can't understand the Q

NB: dh/dt = dvdh / dtdv

alright thanks anyways bro. And i got dh/dt = dh/dv x dv/dt , right?

Reply 1118

Fudge2

5

When working out whether two lines are parallel/skew/intersecting, what is happening geometrically when you solve using the first two equations and get values for lambda and mu but the third equation isn't satisfied? I know that this means I have to say that the lines aren't intersecting but what's going on when I'm doing all of that? :smile:

edit: thinking about it, is it that you've shown a point exists where two of the components are the same but the third component is different on both lines so obvs they don't intersect?