FIND THE TOTAL SURFACE AREA OF GIVEN CUBOID OR RECTANGULAR PRISM

Problem 1 :

Solution:

Given, length = 5 cm

Breadth = 3 cm

Height = 4 cm

Total surface area of rectangular prism = 2(lb + bh + lh)

= 2((5×3) + (3×4) + (5×4))

= 2(15 + 12 + 20)

= 2(47)

= 94 cm²

Problem 2 :

Solution:

Given, length = 12 in.

Breadth = 8 in.

Height = 4 in.

Total surface area of rectangular prism = 2(lb + bh + lh)

= 2((12×8) + (8×4) + (12×4))

= 2(96 + 32 + 48)

= 2(176)

= 352 in².

Problem 3 :

Solution:

Given, length = 30 cm

Breadth = 5 cm

Height = 40 cm

Total surface area of rectangular prism = 2(lb + bh + lh)

= 2((30×5) + (5×40) + (30×40))

= 2(150 + 200 + 1200)

= 2(1550)

= 775 cm²

Problem 4 :

Solution:

Given, length = 15 feet

Breadth = 3 feet

Height = 3 feet

Total surface area of rectangular prism = 2(lb + bh + lh)

= 2((15×3) + (3×3) + (15×3))

= 2(45 + 9 + 45)

= 2(99)

= 49.5 feet²

Problem 5 :

Solution:

Given, side = 5 cm

Surface area of cube = 6s²

= 6(5)²

= 6(25)

SA = 150 cm²

Problem 6 :

Find the surface area of a rectangular prism that has a length of 8 inches, a width of 3 inches, and a height of 6 inches.

Solution:

Given, length = 8 inches

Breadth = 3 inches

Height = 6 inches

Total surface area of rectangular prism = 2(lb + bh + lh)

= 2((8×3) + (3×6) + (8×6))

= 2(24 + 18 + 48)

= 2(90)

= 45 inches²

Problem 7 :

A box that is 15 inches wide, 25 inches high, and 2 inches thick is to be wrapped in gift paper. How many square inches of gift paper are needed?

Solution:

Given, wide = 15 inches

Height = 25 inches

Thick = 2 inches

Total surface area of rectangular prism = 2(lb + bh + lh)

= 2((15×25) + (25×2) + (15×2))

= 2(375 + 50 + 30)

= 2(455)

= 227.5 inches²

Hence, 227.5 square inches of gift paper are needed.