Maths help please: area in a quadralateral?

[Oakie]

So I'm doing some landscaping and laying bark in an area at the back of our house.

The shape I'm working with is a quadralateral with end lengths of 2 metres and 5 metres and side lengths of 7.3 metres and 7.8 metres.

A) how many square metres is that?

B) how many cubic metres of bark would it take to fill that area 1cm deep? (it'll be deeper than that but if I have the 1cm calc I can work out 3cm, 5cm etc)

Yes I failed school cert maths. Famously at a post office training course when we had to do a similar exercise but around estimating quantities of paint to paint a room, where others came up with about 17litres, I came up with about 20,000 litres. I of course had filled the room with paint. Consequently when these questions come up, I seek help.

[bogan]

Quantity could vary depending on the angles between them lengths, are any a 90 deg corner?

:lol: at your paint calculations

[Zedder]

Multiply the length by the width to get square metres.

For cubic metres just do the same as above but multiply by depth. You must use the same units of measurement all through the equation though ie: Don't use metres for length and width then stay with centimetres for depth. EG: 50cm = 500mm or .5 of a metre.

[yachtie10]

So I'm doing some landscaping and laying bark in an area at the back of our house.

The shape I'm working with is a quadralateral with end lengths of 2 metres and 5 metres and side lengths of 7.3 metres and 7.8 metres.

A) how many square metres is that?

B) how many cubic metres of bark would it take to fill that area 1cm deep? (it'll be deeper than that but if I have the 1cm calc I can work out 3cm, 5cm etc)

Yes I failed school cert maths. Famously at a post office training course when we had to do a similar exercise but around estimating quantities of paint to paint a room, where others came up with about 17litres, I came up with about 20,000 litres. I of course had filled the room with paint. Consequently when these questions come up, I seek help.

rough calc is (2+5/2)*(7.3+7.8/2) to give square metres of 26.25
1 cm deep would be divide by 100 to give cubic metres of .2625 which is the same as 26 litres

only rough as dont know the shape

[slofox]

Approx 25.2 square metres

You'd need about 0.252 cubic metres to cover it to 1cm (1% of the area since 1cm is 1% of a metre.)

This is approximate since my diagram is only roughly to scale...

I think.

[Oakie]

Quantity could vary depending on the angles between them lengths, are any a 90 deg corner?

:lol: at your paint calculations

The angles at the ends of the 7.3 metre side are both 90 deg.

[bogan]

The angles at the ends of the 7.3 metre side are both 90 deg.

You sure? doesn't really fit with the 7.8m figure for the opposite side.

[slofox]

So in fact you have a rectangle plus a triangle.

Your rectangle is 7.3 x 2.0 square metres. =14.4 square metres.

Your triangle is 7.3m high and 3m across the base. Area of a triangle is "half the base by perpendicular height". Which is 1.5 x 7.3 metres. =10.95 square metres.

Add 'em together and you have 25.35 square metres.

Cover 1cm deep you need .2535 cubic metres. Or 253.5 litres.

[slofox]

1 cm deep would be divide by 100 to give cubic metres of .2625 which is the same as 26 litres


260 litres? 1000 litres per cubic metre?


Yachtie's calcs and mine are pretty close. Suffice to say that if you bought a cubic metre of bark it would cover to around 4cm deep...

[Oakie]

Multiply the length by the width to get square metres.
. I could do that bit if it was a rectangle but the odd shape threw me.

I've realised now that as the 7.3m side had 90 degree angles at each end I could have called the shape a rectangle by saying both ends were 5m and then working out the area of that thoeretical shape. I could then deduct the area of the additional triangle I have just added to the original shape to get the true area. Now, where is Excel ...
5m x 7.3m = 36.5m less 7.3m (the length of the side with then 90deg angles) x 3m (the end of the end of the triangle I added to make my odd shape a rectangle) x .5 = 10.95 Now 36.5 - 10.95 = 25.55sqm. Damned close to what you fine gentlemen achieved so I'm happy with that. I now know that a 2 cubic metre trailer load will cover the area to a depth of about 8cm which is more than enough.
Thanks folks!

[Oakie]

So in fact you have a rectangle plus a triangle.

Your rectangle is 7.3 x 2.0 square metres. =14.4 square metres.

Your triangle is 7.3m high and 3m across the base. Area of a triangle is "half the base by perpendicular height". Which is 1.5 x 7.3 metres. =10.95 square metres.

Add 'em together and you have 25.35 square metres.

Cover 1cm deep you need .2535 cubic metres. Or 253.5 litres.

Ha ha. I guess i was working that out as you posted it here. Slightly different method but same answer so it must be right. Cheers!

[Oakie]

You sure? doesn't really fit with the 7.8m figure for the opposite side.
One end was 2 metres, the other was 5 which created the extra length on the other side.

[bogan]

One end was 2 metres, the other was 5 which created the extra length on the other side.

Yeh my head told me that would make it more than 7.8 though. But a calculator tells me it would make 7.9, close enough.

[Oblivion]

I tried calculating it and got 28.25m2 as the area. So thats 0.2825m3 per cm deep.

[Bikemad]

i get 15 ohms................no wait!!

[slofox]

Yeh my head told me that would make it more than 7.8 though. But a calculator tells me it would make 7.9, close enough.

7.89240140895...not that I'm obessive compulsive or anything you unnerstand:whistle:

[bogan]

7.89240140895...not that I'm obessive compulsive or anything you unnerstand:whistle:

nah, neither am I :innocent:

7.892401408950256883785263488642

[Oblivion]

nah, neither am I :innocent:

7.892401408950256883785263488642

3.141592653589793238462643383279502884197169399375 10582097494459230781640628620899862803482534211706 79

Is this enough? :innocent:

[Pussy]

Just keep shovelling bark in to the garden till it's full, then stop.

You're welcome! :)

[slofox]

nah, neither am I :innocent:

7.892401408950256883785263488642

My calculator only goes to 12 places...:weep:

[slofox]

Just keep shovelling bark in to the garden till it's full, then stop.

You're welcome! :)

Geez! Never though of that! You must be brainy arncha!

[tigertim20]

So I'm doing some landscaping and laying bark in an area at the back of our house.

The shape I'm working with is a quadralateral with end lengths of 2 metres and 5 metres and side lengths of 7.3 metres and 7.8 metres.

A) how many square metres is that?

B) how many cubic metres of bark would it take to fill that area 1cm deep? (it'll be deeper than that but if I have the 1cm calc I can work out 3cm, 5cm etc)

Yes I failed school cert maths. Famously at a post office training course when we had to do a similar exercise but around estimating quantities of paint to paint a room, where others came up with about 17litres, I came up with about 20,000 litres. I of course had filled the room with paint. Consequently when these questions come up, I seek help.

you could always cheat.
add the lengths of the sides together. 2+5+7.3+7.8 = 22.1
the divide by 4 for a perfect sqaure and go from there!

[Zedder]

I could do that bit if it was a rectangle but the odd shape threw me.

I've realised now that as the 7.3m side had 90 degree angles at each end I could have called the shape a rectangle by saying both ends were 5m and then working out the area of that thoeretical shape. I could then deduct the area of the additional triangle I have just added to the original shape to get the true area. Now, where is Excel ...
5m x 7.3m = 36.5m less 7.3m (the length of the side with then 90deg angles) x 3m (the end of the end of the triangle I added to make my odd shape a rectangle) x .5 = 10.95 Now 36.5 - 10.95 = 25.55sqm. Damned close to what you fine gentlemen achieved so I'm happy with that. I now know that a 2 cubic metre trailer load will cover the area to a depth of about 8cm which is more than enough.
Thanks folks!

Glad it worked out alright for you. For all intents and purposes, it's really only a rectangle.

When I was in roading we had to worry about things like bulkage and shrinkage, which made it a bit more complex.

[Oakie]

When I was in roading we had to worry about things like bulkage and shrinkage, which made it a bit more complex.

All I'm really worried about now is cats shitting in it!

[Zedder]

All I'm really worried about now is cats shitting in it!

Yep, a giant cat toilet. You could fence it of course but it is big. There was a product called "Skunk shot" around at garden centres a while back. All it takes is a dab every so often around the perimeter but cats and dogs absolutely hate it.

[Oakie]

Yep, a giant cat toilet. You could fence it of course but it is big. There was a product called "Skunk shot" around at garden centres a while back. All it takes is a dab every so often around the perimeter but cats and dogs absolutely hate it.

To try to avoid that I've gone for the biggest bark nugget size available. Hopefully it will be as appropriate to a cat looking for a dunny as it would be for us wiping our arse with a book instead of toilet paper

[Zedder]

To try to avoid that I've gone for the biggest bark nugget size available. Hopefully it will be as appropriate to a cat looking for a dunny as it would be for us wiping our arse with a book instead of toilet paper

Fingers crossed then.