Mathematics: Post your doubts here!

[Aarjit]

okay I didn't understand much probably because I am used to equating two directional vectors and solving them with the cross product.I then take the position vectors of the line on which the plane contains and then equate the result of cross product subsequently to find 'd'.
when the question says its perpendicular to OAB,why do we consider OP at all?

...because OP is perpendicular to AB and so is plane OAB! OP falls in the region of OAB.
Saying that OP is in the plane OAB is exactly like saying ~ AB is in the plane which you need to solve for.

P.S. A rough sketch will make the situation easier to perceive.

 

[2pac]

...because OP is perpendicular to AB and so is plane OAB! OP falls in the region of OAB.
Saying that OP is in the plane OAB is exactly like saying ~ AB is in the plane which you need to solve for.

P.S. A rough sketch will make the situation easier to perceive.

okay thanks anyways,will just hope a question like this doesn't come.

 

[leadingguy]

http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_s10_qp_31.pdf
http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_s10_ms_31.pdf

question 7 part ii)
can any one give a rough idea of the sketch????

 

[GoodRobot]

http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_w11_qp_32.pdf

not getting question 10(ii).can someone plz do the correct sketching of the Argand diagram

 

[Aarjit]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_33.pdf

how to differentiate no.2? I know its using division differentiation but can anyone show me? thank you.

y = (e^2x)/[1+(e^2x)]

dy = 2e^(2x)[1+e^(2x)] - e^(2x).2e^(2x)
dx.....clever,eh?[1+e^(2x)]^2
.....= 2e^(2x) + 2e^(4x) - 2e^(4x)
......................[1+e^(2x)]^2
.....= ___2e^(2x) ___
.............[1+e^(2x)]^2
x= ln3;
.....= ___2e^(2.ln3) ___
.............[1+e^(2.ln3)]^2

.....= ___2e^(ln9) ___ = __2*9___ = _18_ = _9_.......Q.E.D
.............[1+e^(ln9)]^2.........[1+9]^2........100.......50

 

[kaz619]

Okay one more doubt, O/N/11 p32 q6 pt. (ii)

http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_w11_qp_32.pdf

thanks

Edit: Changed p31 to p32 , apologies!

 

[angelicsuccubus]

Okay one more doubt, O/N/11 p31 q6 pt. (ii)

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_32.pdf

thanks

you said p31 but you linked p32.. which is it?

 

[kaz619]

you said p31 but you linked p32.. which is it?

Oh god my bad! I meant P32 D:

 

[angelicsuccubus]

Oh god my bad! I meant P32 D:

if you got the first part .. then just substitute the values of R and alpha in Rcos(x-a)=2 and then your x=2theta.. so then get theta

 

[kaz619]

if you got the first part .. then just substitute the values of R and alpha in Rcos(x-a)=2 and then your x=2theta.. so then get theta

Thank you!

 

[Khoo Hing Yee]

Q4(ii).. Why only 2/3 accepted?
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_31.pdf

 

[ALM&B]

Okay one more doubt, O/N/11 p32 q6 pt. (ii)

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_32.pdf

thanks

Edit: Changed p31 to p32 , apologies!

I found Only 1 angle

(2x-71.6) = 50.76
2x = 50.76 + 71.6
2x = 122.36
2x = 122.36 - 90
2x = 32.36
--> (32.36+90) / 2 = 61.2

But I didnt know how they got the second angle :/

 

[angelicsuccubus]

Thank you!

uh I just attempted it and I can't seem to get 10.4... how did they get 10.4?

 

[user]

I found Only 1 angle

(2x-71.6) = 50.76
2x = 50.76 + 71.6
2x = 122.36
2x = 122.36 - 90
2x = 32.36
--> (32.36+90) / 2 = 61.2

But I didnt know how they got the second angle :/

uh I just attempted it and I can't seem to get 10.4... how did they get 10.4?

assalamoalaikum wr wb!

alright...now u know the other angle would be 360 - 50.76 ...right? but that is out of the range given..now remember that in the fourth quadrant angle can either be 360 - x or alternatively be written as "-x "
so we have
(2x-71.6) = 50.76 and (2x-71.6) = - 50.76

that's how u'll get the other angle

 

[GoodRobot]

I found Only 1 angle

(2x-71.6) = 50.76
2x = 50.76 + 71.6
2x = 122.36
2x = 122.36 - 90
2x = 32.36
--> (32.36+90) / 2 = 61.2

But I didnt know how they got the second angle :/

for second angle : 2x-71.57=360-50.768
2x=380.8-360
2x=20.802
x=10.4

 

[sea_princess]

Q4(ii).. Why only 2/3 accepted?
http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_31.pdf

because other factors are negative ( -2, - 3/4) and there is no log of negative values

 

[RGBM211]

http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_s11_qp_31.pdf
http://www.xtremepapers.com/papers/...S Level/Mathematics (9709)/9709_s11_ms_31.pdf

can someone do no.6 mmm confused


question no.8 how to show the arguement u is PIE/2 i knw its pie by 2 since i got u=-3i but how to show should i draw a graph or i should just say that the cordinates (0,-3i) lies on the y axis thus the angle made with the x axis is -pie/2
Anyone :?


and question no.10

well the above questions are my prev post which no1 has answerd

 

[ALM&B]

assalamoalaikum wr wb!

alright...now u know the other angle would be 360 - 50.76 ...right? but that is out of the range given..now remember that in the fourth quadrant angle can either be 360 - x or alternatively be written as "-x "
so we have
(2x-71.6) = 50.76 and (2x-71.6) = - 50.76

that's how u'll get the other angle

Thank you that totally makes sense!

 

[angelicsuccubus]

for second angle : 2x-71.57=360-50.768
2x=380.8-360
2x=20.802
x=10.4

wth? don't you just divide it by 2 after getting 380.8?

 

[ALM&B]

for second angle : 2x-71.57=360-50.768
2x=380.8-360
2x=20.802
x=10.4

umm well aren't we supposed to take into consideration the ranges they gave us?
I dont think they'll give us full on this
but at least u came to know it!
thanks!!