• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Mathematics: Post your doubts here!

Isaac CKR

Isaac CKR

Messages
13
Reaction score
7
Points
13
BreakingBad said:
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?
Click to expand...
Thank you. :) I've done the rest of the question.
 
Tee Kay

Tee Kay

Messages
7
Reaction score
8
Points
3
BreakingBad said:
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.
Click to expand...

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
 

Attachments

  • 2014-01-17 21.49.10.jpg
    2014-01-17 21.49.10.jpg
    742 KB · Views: 5
B

BreakingBad

Messages
165
Reaction score
490
Points
73
Tee Kay said:
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
Click to expand...
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.
 
TheZodiac

TheZodiac

Messages
347
Reaction score
520
Points
73
♫Prince Shah♫ said:
i m not getting answer.................... :(
Click to expand...
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.
 
Last edited:
chishtyguy

chishtyguy

Messages
473
Reaction score
1,511
Points
153
TheZodiac said:
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.
Click to expand...
M=1/2.. You have mistakenly put '-' sign there...
 
S

sitooon

Messages
302
Reaction score
432
Points
28
upload_2014-1-12_12-1-34-png.34407
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!
 
You must log in or register to reply here.
Top