Total surface area of rectangular prism
Post on 05-Jul-2015
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Shefsyn. K. Y.Reg: No: 13 386 006
B: Ed: (Mathematics)St. Thomas Training College
Total Surface Area of Rectangular Prism
Each side of a rectangular prism is called a face.
A rectangular prism has six faces.
In a rectangular prism there are 3 pairs of opposite and equal sides.The first pair is the red face
7 cm (l)
4 cm (b)
10 cm (h)
10 cm (h
7 cm (l)
We can see another face - just like the red face. That is on the back.
7 cm(l)
10 cm(h)
7 cm(l)
10 cm(h)
Now there are 2 rectangles that each have an area of 70cm² ie lh+lh=2lh
l x h= 7 x 10= 70cm²
70 cm2
70 cm2
The second pair is the blue face
10 cm (h)
4 cm (b)
7 cm (l)4 cm (b)
10 cm (h)
We can see another face - just like the blue face. That is on the left side.
10 cm (h)
4 cm (b)4 cm (b)
10 cm (h)
Now there are 2 rectangles that each have an area of 40cm² ie bh+bh=2bh
40cm²
40cm²
b x h= 4 x 10= 40cm²
The third pair is the green face
10 cm (h)
4 cm (b)
7 cm (l)
7 cm (l)
4 cm (b)
We can see another face - just like the green face. That is on the bottom.
4 cm (b)4 cm (b)
7 cm (l) 7 cm (l)
Now there are 2 rectangles that each have an area of 28cm² ie lb+lb=2lb
28cm²
28cm²
l x b= 7 x 4= 28cm²
Now we just need to add all the areas of the sides together.
+ +
++28cm2
40cm270cm2
70cm2
40cm2 28cm2
The total surface area for this rectangular prism is
70+70+40+40+28+28=276 cm²Ie
2lb+ 2bh+ 2lh=2(lb+bh+lh)
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