Total surface area of rectangular prism

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)