Mathematics: Post your doubts here!

[AlishaK]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s12_qp_32.pdf
Q4 ?! the identity. just show me a couple of steps..i'lll do the rest.
Thanks a lot

 

[Esme]

aoa,plz tel me why we subtract basic angle from pi in complex num? and how to draw loci in argand diagram?

Loci in Argand diagrams

 

[Esme]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_32.pdf
Q4 ?! the identity. just show me a couple of steps..i'lll do the rest.
Thanks a lot

1/sin2x = 1/cosx + cosx/sinx
1/2sinxcosx = (sinx+cos^2x)/cosxsinx
1/2 = sinx + (1-sin^2x)
1/2 = sinx - sin^2x +1

Now I'm sure you can solve the quadratic equation

 

[Esme]

Can anyone solve this identity for me? cos4x-4cos2x+3=8sin^4x

cos4x - 4cos2x + 3
cos(2x+2x) - 4( 1- 2sin^2x) + 3
cos2xcos2x-sin2xsin2x -4 + 8sin^2x +3
(1-2sin^2x)^2 - (2sinxcosx)^2 + 8sin^2x -1
1-4sin^2x+4sin^4x - 4sin^2x(1-sin^2x) + 8sin^2x -1
4sin^2x + 4sin^4x - 4sin^2x + 4sin^4x
8sin^4x

I may have skipped a few steps but remember you have to replace all the cos with sin, wherever you can.

 

[AlishaK]

1/sin2x = 1/cosx + cosx/sinx
1/2sinxcosx = (sinx+cos^2x)/cosxsinx
1/2 = sinx + (1-sin^2x)
1/2 = sinx - sin^2x +1

Now I'm sure you can solve the quadratic equation

Argh! we had to use both the sides?! I was only using/solving LHS to prove RHS?!
Thanks a lot Esme!!
Jazak Allah khair!

 

[AlishaK]

Argh! we had to use both the sides?! I was only using/solving LHS to prove RHS?!
Thanks a lot Esme!!
Jazak Allah khair!

just realised the question says 'Solve' not 'Prove'...Thanku anyhow.

 

[Esme]

Argh! we had to use both the sides?! I was only using/solving LHS to prove RHS?!
Thanks a lot Esme!!
Jazak Allah khair!

Yeah I thought that might be your mistake
Anytime sis

 

[SararaIH]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w09_qp_31.pdf

Can someone please give me the solution to the whole of Q 6) , Q7 iv) and Q 10i

 

[AlishaK]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_s12_qp_32.pdf
Q7 iii) I know how to do it. But what exactly do I have to show for '3 marks' ?!
Esme
Thank u! :')

 

[TaffsAsLevel]

Will we get full marks if we got our final answer correct but very short working? It is 6 marks but I got correct? Or you have to do the long way? Like if Find length AB given the line r=something and meets at plane p at A and plane q at B. Find AB length (June 2010 paper 32)

 

[Zsiddiqui]

Reposting:



xhizors Ashique or anyone taking statistics?

Sum of (fx) / sum of (f) = 27.5
(10+15f+330+240)/ 17+f
580+15f = (17+f)*(27.5)
580+15f = 467.5 + 27.5f
112.5 = 12.5f
f = 9

Total number of children = 2+9+11+4 = 26

 

[Arjun Dhanak]

Hi. I need to know when we use vector cross product and what the reason for using it is. What is the outcome of doing vector product?
Thanks in advance.
-Arjun

 

[Soldier313]

Sum of (fx) / sum of (f) = 27.5
(10+15f+330+240)/ 17+f
580+15f = (17+f)*(27.5)
580+15f = 467.5 + 27.5f
112.5 = 12.5f
f = 9

Total number of children = 2+9+11+4 = 26

Thanx sis for that, the pro is i know the method, however, i was using 4.5 rather than 5, 14.5 rather than 15 etc
so my qn is how do i know when i am supposed to use what, coz there are some circumstances when we'd have to use the 4.5 rather than 5 etc.

 

[Arjun Dhanak]

Hi. I need to know when we use vector cross product and what the reason for using it is. What is the outcome of doing vector product?
Thanks in advance.
-Arjun

 

[SararaIH]

http://papers.xtremepapers.com/CIE/...S Level/Mathematics (9709)/9709_w09_qp_31.pdf

Can someone please give me the solution to the whole of Q 6) , Q7 iv) and Q 10i

 

[syed1995]

Reposting:



xhizors Ashique or anyone taking statistics?

Link?

I would suggest that you use... https://www.xtremepapers.com/commun...tics-doubt-post-your-doubts-here.25911/page-6 to ask for S1 questions .. as most of the people are not posting their S1 questions/watching this thread.. because of the P3 on Monday..

 

[Soldier313]

Link?

I would suggest that you use... https://www.xtremepapers.com/commun...tics-doubt-post-your-doubts-here.25911/page-6 to ask for S1 questions .. as most of the people are not posting their S1 questions/watching this thread.. because of the P3 on Monday..

oh right, thank you.

 

[Esme]

Will we get full marks if we got our final answer correct but very short working? It is 6 marks but I got correct? Or you have to do the long way? Like if Find length AB given the line r=something and meets at plane p at A and plane q at B. Find AB length (June 2010 paper 32)

It's better you show all the steps for whichever method you choose. Because with vectors there's always more than one way to obtain answer. You can do whatever way seems easy or short to you but show how you've done it.

 

[Esme]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s12_qp_32.pdf
Q7 iii) I know how to do it. But what exactly do I have to show for '3 marks' ?!
Esme
Thank u! :')

Here's what i've done:

argu = arg( (1+2i)/(1-3i) )
argu = arg(1+2i) - arg(1-3i)
arg(-1/2 + i/2) = tan^-1(2) - tan^-1(-3)
tan^-1(-1) = tan^-1(2) + tan^(3)
3π/4 = tan^-1(2) + tan^-1(3)

Hope you got it

 

[Soldier313]

Aoa wr wb
Can someone please help me, for qn 10 ii of this paper, while integrating, i don't get where the -ve sign comes before the 3/2
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s07_qp_3.pdf
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s07_ms_3.pdf
Thank you