AS-Level Maths Help??

The diagram
(link (http://i1193.photobucket.com/albums/aa342/Randomphysics/Diagram.jpg?t=1288095261 ) ) shows the net of a cylindrical container of radius r cm and height hcm. The full width of the metal sheet from which the container is made is 1m, and the shaded area is waste. The surface area of the container is 1400pi cm^2.

Write down a pair of simulataneous equations for r and h, and solve... finding r and h....

how do you find the equations? i am so confused :frown:

Reply 1

ht1234

1

i think you take the formula of the s.a of the cylinder and then you arrange it to find r. that would be your first equation. r= .......
then, you do the same but this time you rearrange it to get h alone to find it. that would be your second equation.

now that you've got the two equations, just solve them like you would normally solve simultaneous equations and find the values of r and h.

Hope this helps and also that this is right haha.

Reply 2

sytner9

The Sim Eq's are:
1) 4r + h =1
2) 2*(2*pi*r^2) + h(2*pi*r) = 1400*pi

Then just solve. The h(2*pi*r) bit is for the surface area of the middle bit.

Reply 3

sytner9

The Sim Eq's are:

1) 4r + h =1
2) 2*(2*pi*r^2) + h(2*pi*r) = 1400*pi

Then just solve. The h(2*pi*r) bit is for the surface area of the middle bit.

Reply 4

a-spiringmedic

OP

11

Original post by ht1234

i think you take the formula of the s.a of the cylinder and then you arrange it to find r. that would be your first equation. r= .......
then, you do the same but this time you rearrange it to get h alone to find it. that would be your second equation.

now that you've got the two equations, just solve them like you would normally solve simultaneous equations and find the values of r and h.

Hope this helps and also that this is right haha.