To find the surface area of a rectangular prism, you need to know the lengths of all its sides. In this case, the given dimensions are:
Length = 21.5 mm
Height = 5 mm
Width = 4 mm
The surface area of a rectangular prism is calculated by adding the areas of all its six faces. Each face is a rectangle, and its area can be found by multiplying the length and width of the rectangle.
To calculate the surface area, follow these steps:
1. Calculate the area of the top and bottom faces:
- The area of the top face = length × width
- The area of the bottom face = length × width
2. Calculate the area of the front and back faces:
- The area of the front face = height × width
- The area of the back face = height × width
3. Calculate the area of the left and right faces:
- The area of the left face = length × height
- The area of the right face = length × height
4. Add up the areas of all six faces to get the total surface area of the rectangular prism.
Now, let's calculate the surface area of the given rectangular prism:
Top and bottom faces:
= (21.5 mm × 4 mm) + (21.5 mm × 4 mm)
= 86 mm^2 + 86 mm^2
= 172 mm^2
Front and back faces:
= (5 mm × 4 mm) + (5 mm × 4 mm)
= 20 mm^2 + 20 mm^2
= 40 mm^2
Left and right faces:
= (21.5 mm × 5 mm) + (21.5 mm × 5 mm)
= 107.5 mm^2 + 107.5 mm^2
= 215 mm^2
Total Surface Area:
= 172 mm^2 + 40 mm^2 + 215 mm^2
= 427 mm^2
Therefore, the correct answer is option B: 427 mm^2.
M, S, E 
Explain Bot