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## Find the surface area of a rectangular prism with the dimensions of 5 by 5 by 4 units.

# Surface area of a rectangular prism formula

**Method 2.**

Formula for *surface area* = P x h + 2B

**Step 1.** If you unfolded the prism, the sides would look like this.

- P = Perimeter of the prism

**Method 2.** Use the formula

** P x h + 2B**

## Finding the surface area of a rectangular prism

## Find the surface area of a rectangular prism with the dimensions of 6 by 4 by 3 units.

**Method 1.**

**Step 1.** Multiply length times width of the front and back side 6 x 3 = 18

Multiply 18 x 2 because there is a front and a back side. 18 x 2 = **36**

**Step 2.** Repeat for the two ends and the top and bottom of the rectangular prism

4 x3 = 12

12 x 2 =** 24**

6 x 4 = 24

24 x 2 = **48**

**Step 3.** Add these three areas together for the total surface area

36 + 24 + 48 = **108 square units**

Add these four sides together for the perimeter

6 + 4 + 6 + 4 = 20

**Step 2. **Multiply the perimeter times the height

20 x 3 = 60

**Step 3. **Compute your base areas 6 x 4 =24

Multiply your base area times two for your total base area 24 x 2 = 48

**Step 4. **Add your perimeter area to your total base area for your total surface area

48 + 60 = **108 square units**

**Method 1.** Add area of each side together

5 x5 = 25 x 2 = 50

5 x4 = 20 x 2 = 40

5 x 5 = 25 x 2 = 50

Add these side areas for total surface area

50 + 40 + 50 = 140 square units

**Method 2**.

**Step 1.** Find the perimeter

5 + 4 + 5 + 4 = 18

**Step 2**. Multiply perimeter x height

18 x 5 = 90

**Step 3.** Add the perimeter from step 2 to area of two bases

90 + 2(5 x5 ) = 90 + 50 = 140 units squared

### Formula for surface area of a rectangular prism video answer.

**Method 1.** You can add the area of each pair of sides of the *rectangular prism.*