Question

Hi !

activity -

Aim- to verify the formula for surface area of a cuboid by activity method .

( you can tell - material required , procedure and observation )
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Answer 1

Answer:

Aim-

To verify the formula for surface area of a cuboid by activity method.

Materials required -

A cuboidal cardboard box, sketch pens or pens , plane sheet of paper, pair of scissors and sellotape.

Procedure-

1. Take an empty cuboidal cardboard box and mark its length, breadth and height as I, b and h respectively (as shown in Figure 1).

2. Colour the three pairs of opposite faces with three different colours.

3. Cut out the six faces and paste them on a plane sheet of paper as shown in Figure 2.

4. Find the area of each face.

5. Add the area of all the faces to find the surface area of the cuboidal cardboard box.

Obesrvation -

1. Area of top and base

= _ × _ + _ × _ = 2 ( _ × _ ) = 2 lb

2. Area of two side faces

= _ × _ + _ × _ = 2 ( _ × _ ) = 2 bh

3. Area of front and back face

= _ × _ + _ × _ = 2 ( _ × _ ) = 2 hl

⠀

Surface area of the cuboidal box

= Area of (top and base + two side faces + front and back faces)

= 2 Area of (top face + one side face + front face)

= 2 (Ib + bh + hl)

Hence, the formula for the surface area of a cuboid is verified. $\green{\bigstar}$

Note: In case of a cube, length = breadth = height

• Surface area of a cube = 2(side² + side² + side²) = 2(3 side²) = 6 side²

Answer 2

Answer:

1. Take an empty cuboidal cardboard box and mark its length, breadth and height as I, b and h respectively .

2. Colour the three pairs of opposite faces with three different colours.

3. Cut out the six faces and paste them on a plane sheet of paper as shown in .

4. Find the area of each face.

5. Add the area of all the faces to find the surface area of the cuboidal cardboard box.