Question

4. Total surface area of cuboid is 166 cm². Find its length if breadth and height are 5cm and
4cm respectively.​

Answer 1

Answer :-

Given :-

• Total surface area of cuboid = 166 cm²

• Breadth = 5 cm

• Height = 4 cm

To Find :-

• Length, l

Solution :-

We know that,

Surface area of cuboid = 2 ( lb + bh + hl )

Substituting the values :-

→ 166 = 2 ( l × 5 + 5 × 4 + 4 × l )

→ 166 / 2 = 5l + 20 + 4l

→ 83 = 9l + 20

→ 9l = 83 - 20

→ 9l = 63

→ l = 63 / 9

→ l = 7

Length of cuboid = 7 cm

Answer 2

Answer:

Let, length of cuboid be x.

breadth = 5cm

height =4cm

total surface area = 166 cm

Total surface area of cuboid = 2 * (lb + bh + hl )

166 = 2*(x*5 + 5*4 + 4*x)

166 = 2*(5x + 20 + 4x)

166 = 2*(9x + 20)

166 = 2*9x + 2* 20

166 = 18x + 40

166-40 = 18x

126 = 18x

126÷ 18 = x

7 = x

therefore, vale of x = 7

length = 7cm

I hope so you understand