Quick Maths! Lesson #01
Is there a quick way to find the surface area of a rectangular prism?
We know there are 3 PAIRS of unique faces.
Face 1 = Length × Height
Face 2 = Height × Breadth
Face 3 = Breadth× Length
To find the total surface area, we just add the 3 faces and multiply that number by 2.
Example
Find the surface area of the following rectangular prism.
Face 1 = 20 x 10 = 200 cm2
Face 2 = 15 x 20 = 300 cm2
Face 3 = 15 x 10 = 150 cm2
Surface Area = (200 + 300 + 150) x 2 = 1,300 cm2.
Try these questions yourself!
Find the surface area of a rectangular prism whose dimensions are:
1. 10 cm x 8 cm x 6 cm
Answer
(80 + 60 + 48) x 2 = 376 cm2
2. 15 m by 3 m by 3 m
Answer
(45 + 45 + 90) × 2 = 360 cm2
