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secondary 4 | E Maths
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How do you solve this question? I factorised 144 (2^4 X 3^2) already but I don't know how to find the height
Date Posted: 5 years ago
Views: 596
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VERRY SORRY! Problem uploading Answer!!!
Answer as follows:
Secondary 4 Mathematics:
Each side of the cuboid is > 2cm
Length (L) of cuboid can be 3cm or greater
Width (W) of cuboid can be 3cm or greater
2L + 2W = 22 cm
L + W = 11 cm
If L = W
Then L = 5.5cm (But the cuboid is made up of 1 cm cubes. So the length and width must be whole nos. Therefore L is not equal to W)
Since L + W = 11 cm
If L = 3 cm, then W = 8 cm
If L = 4 cm, then W = 7 cm
If L = 5 cm, then W = 6 cm
Let calculate the area of the top of the cuboid according to the 3 possibilities of the length of L and W as listed above:
Possibility 1 :
Area of the top of cuboid = 3x8 = 24 cm^2
Possibility 2 :
Area of the top of cuboid = 4x7 = 28 cm^2
Possibility 3 :
Area of the top of cuboid = 5x6 = 30 cm^2
The height of the cuboid = 144 / area of cuboid top
Substitute each of the above 3 possibilities of area of cuboid top
as follows:
1) 144 / 24 = 6
2) 144 / 28 = 5.14
3) 144 /30 = 4.8
Therefore the height of the cuboid = 6 cm (because it is made up of 1 cm cubes which is whole number)
Answer as follows:
Secondary 4 Mathematics:
Each side of the cuboid is > 2cm
Length (L) of cuboid can be 3cm or greater
Width (W) of cuboid can be 3cm or greater
2L + 2W = 22 cm
L + W = 11 cm
If L = W
Then L = 5.5cm (But the cuboid is made up of 1 cm cubes. So the length and width must be whole nos. Therefore L is not equal to W)
Since L + W = 11 cm
If L = 3 cm, then W = 8 cm
If L = 4 cm, then W = 7 cm
If L = 5 cm, then W = 6 cm
Let calculate the area of the top of the cuboid according to the 3 possibilities of the length of L and W as listed above:
Possibility 1 :
Area of the top of cuboid = 3x8 = 24 cm^2
Possibility 2 :
Area of the top of cuboid = 4x7 = 28 cm^2
Possibility 3 :
Area of the top of cuboid = 5x6 = 30 cm^2
The height of the cuboid = 144 / area of cuboid top
Substitute each of the above 3 possibilities of area of cuboid top
as follows:
1) 144 / 24 = 6
2) 144 / 28 = 5.14
3) 144 /30 = 4.8
Therefore the height of the cuboid = 6 cm (because it is made up of 1 cm cubes which is whole number)
Hi
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I tried using differentiation method, but it was complicated and the answer I got was in decimal. So, I tried using the simplest method to solve this question. I am not whether your teacher will accept. I hope it helps.
Date Posted:
5 years ago
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