Mathematics: Post your doubts here!

[TheZodiac]

I need help with this. Stuck at part (i) now. View attachment 34491

dx/dt = k(100-x)
put the values given and solve for k:
1.9/100-5 = k
k = 0.02

 

[BreakingBad]

Hi, i'm stuck at figuring whats the values of the angles are as i haven't studied trigonometry yet, so if anyone can help me that'd be great

You can also draw the same shape as shown in the image attached. Then use cosine rule and sine rule to find the angles x and y. Use 2x and 2y to calculate arc lengths and accordingly the perimeter.

8 Friends are to make a journey in 2 taxis,with four people in each taxi. In how many ways can this be done ?

Please help me solve this problem

8C4 * 8C4 = 4900 (I think. Permutations and combination questions are really confusing.)

I need help with this. Stuck at part (i) now. View attachment 34491

dx/dt is directly proportional to (100-x)
dx/dt = k(100-x)
Substitute the given values and find k.
1.9/100-5 = k
k = 0.02

Do you need help with the rest of the question as well?

 

[Isaac CKR]

You can also draw the same shape as shown in the image attached. Then use cosine rule and sine rule to find the angles x and y. Use 2x and 2y to calculate arc lengths and accordingly the perimeter.


8C4 * 8C4 = 4900 (I think. Permutations and combination questions are really confusing.)



dx/dt is directly proportional to (100-x)
dx/dt = k(100-x)
Substitute the given values and find k.
1.9/100-5 = k
k = 0.02

Do you need help with the rest of the question as well?

Thank you. I've done the rest of the question.

 

[Tee Kay]

You can also draw the same shape as shown in the image attached. Then use cosine rule and sine rule to find the angles x and y. Use 2x and 2y to calculate arc lengths and accordingly the perimeter.

i did that and the final result was 51.2 while the textbook's final answer is 85.6 , either your method is wrong or i didn't implement it correctly (see attachment) or the textbook is wrong which has plenty of errors

 

[BreakingBad]

i did that and the final result was 51.2 while the textbook's final answer is 85.6 , either your method is wrong or i didn't implement it correctly (see attachment) or the textbook is wrong which has plenty of errors

The text book is right and my method is right as well. Your implementation was correct till finding the arc lengths but you calculated the perimeter wrongly. The actual perimeter of the shape means the outer arcs of both the circles combined. The outer arc is calculated as follows: Circumference - inner arc. Find the outer arcs of both the circles and add them. The answer is 85.6.

 

[♫Prince Shah♫]

i m not getting answer....................

 

[TheZodiac]

i m not getting answer....................

Put y = o in the given equation and you'll find the value of co-ordinates of A.

And the m for the equation can simply be derived by making it equal to y = mx + c.
From here you can find the value of m which is 1/2 so the m for perpendicular would be -2

you've the value of m and now you can make an equation in terms of x and y
(y+3) =-2(x -10)
y+3 = -2x +20
y=2x +17

Equate it in the first equation and you'll get the co-ordinates of B.
Now apply the mid-point formula because the distance between AB and BC is equal, you'll get the co-ordinates of point C.

 

[chishtyguy]

Put y = o in the given equation and you'll find the value of co-ordinates of A.

And the m for the equation can simply be derived by making it equal to y = mx + c.
From here you can find the value of m which is -1/2 so the m for perpendicular would be 2

you've the value of m and now you can make an equation in terms of x and y
(y+3) =2(x -10)
y+3 = 2x -20
y=2x -23

Equate it in the first equation and you'll get the co-ordinates of B.
Now apply the mid-point formula because the distance between AB and BC is equal, you'll get the co-ordinates of point C.

M=1/2.. You have mistakenly put '-' sign there...

 

[TheZodiac]

M=1/2.. You have mistakenly put '-' sign there...

Thanks for pointing it out. I've corrected it.

 

[chishtyguy]

i m not getting answer....................

Is B(8.4,6.2) and C(16.8, 10.4) ??

 

[♫Prince Shah♫]

thanks all

 

[♫Prince Shah♫]

Is B(8.4,6.2) and C(16.8, 10.4) ??

no, B(6,5) and C(12,8)

 

[chishtyguy]

no, B(6,5) and C(12,8)

Sorry bro my bad... I have worked it out though...

 

[♫Prince Shah♫]

make it correct and make me understnd sttep by step..

 

[sitooon]

4

can someone do pat ( ii) ?
marking scheme gave :
(12 + 8) × 0.6sin30 = F(0.6 + 0.6cos30)
F = 5.36
all i know is they used moments about A , and nothing else!

 

[BreakingBad]

4

can someone do pat ( ii) ?
marking scheme gave :
(12 + 8) × 0.6sin30 = F(0.6 + 0.6cos30)
F = 5.36
all i know is they used moments about A , and nothing else!

... I cannot see the image. Can you name the year and question number?

 

[sitooon]

... I cannot see the image. Can you name the year and question number?

First question . http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w12_qp_53.pdf
where shall we put the weights of
semicircular lamina of weight 12 N and a uniform
semicircular arc of weight 8 N .. i mean is it at centre , edge etc

 

[Heyyy]

https://www.xtremepapers.com/community/attachments/9709_w13_qp_32-pdf.34767/
In the question 8 (II),we have to find the least distance of w from z,right?

 

[mmmmmm]

https://www.xtremepapers.com/community/attachments/9709_w13_qp_32-pdf.34767/
In the question 8 (II),we have to find the least distance of w from z,right?

Sorry, i am little weak in these sketches of loci and can u tell me from where did u get these oct/nov papers?
Thanks.

 

[Heyyy]

Sorry, i am little weak in these sketches of loci and can u tell me from where did u get these oct/nov papers?
Thanks.

Someone had posted the Maths p3 paper here