Question

Raju wants to paint a cuboidal box which is 20 cm in length , 15 cm in breadth and 6 cm in depth. Find the area to be painted if the box is open at the top.​

Answer 1

Answer:

ɢɪᴠᴇɴ:-

• Length (l) = 20 cm
• Breadth (b) = 15 cm
• Height (h) = 6 cm

ᴛᴏ ғɪɴᴅ :-

Area of Box open at the top

sᴏʟᴜᴛɪᴏɴ :-

We know that,

Area of Cuboid(Box) = 2(lb + lh + bh)

➮ 2(lb + lh + bh)

➮ 2(20 × 15 + 20 × 6 + 15 × 6)

➮ 2(300 + 120 + 90)

➮ 2(510)

➮ 1020 cm²

Now,

Required area of Box = Area of box - Area of Top

➮ Required area = 1020 - (l × b)

➮ 1020 - (20 × 15)

➮ 1020 - 300

➮ 720 cm²

Hence,

Area of Box to be painted is 720 cm²

TO MORE INFORMATION :-

• Total Surface Area of a Cuboid (TSA) = 2 (lb + bh + lh) square units
• Lateral Surface Area of a cuboid (LSA) = 2h (l+b) square units
• Volume of the cuboid (v) =lbh

Answer 2

Height = 6cm, Breadth = 15cm and Length = 20cm

Formula for painting a cuboidal box with its top open:

TSA of a cuboid - area of rectangle =

2(lb + bh + hl) - lb

=> 2( 20x15 + 15x6 + 6x20 ) - 20x15

=> 2 ( 300 + 90 + 120 ) - 300

=> 2 ( 510 ) - 300

=> 1020 - 300

=> 720 cm^2

The area to be painted if the box is open at the top will be 720 cm^2.

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