Question

Plzz tell me..... I will rate ur answer....
First - fill in the blank if two squares of side a CM are placed side by side then area of the resultant polygon will be______.
2 answer the following a rectangular piece of paper is 44 cm long and 20cm broad it is rolled along its length to form a cylinder find the volume of the cylinder so formed draw figure also
20cm long iron pipe has exterior diameter equal to 25 CM if the thickness of the pipe is 1 cm find the whole surface area of the pipe.
If anyone will give the answer of all these question I will mark her / him Brainliest

Answer 1

Answer:

$1) \: 2 {a}^{2} \: {cm}^{2} \\ \\ 2)1400 \: {cm}^{3} \\ \\ 3) \: 3168 {cm}^{2}$

Step-by-step explanation:

1)if two squares of side a CM are placed side by side then area of the resultant polygon will be______.

Ans: resultant polygon will be a rectangle, with length =2a

breadth = a

Area of rectangle =length×breadth

= 2a×a

$2 {a}^{2} \: sq-cm$

2) A rectangular piece of paper is 44cmlong and 20cm broad it is rolled along its length to form a cylinder find the volume of the cylinder so formed draw figure also.

Ans: on rolling along its length,breadth will become perimeter of base and top of Cylinder

Perimeter of circle= 2πr

$2\pi \: r = 20 \\ \\ r = \frac{20}{2\pi} \\ \\ r = \frac{10}{\pi}$

Volume of cylinder

$= \pi {r}^{2} h \\ \\ = \pi \times \frac{10}{\pi} \times \frac{10}{\pi} \times 44 \\ \\ = \frac{100 \times 7 \times 44}{22} \\ \\ = 100 \times 7 \times 2 \\ \\ = 1400 \: {cm}^{3}$

3) 20cm long iron pipe has exterior diameter equal to 25 CM if the thickness of the pipe is 1 cm find the whole surface area of the pipe.

Ans:

Diameter external =25 cm

Radius , R=12.5 cm

Thickness = 1 cm

Internal diameter= 23 cm

Internal Radius ,r= 11.5 cm

length = 20 cm

Surface area of iron pipe:

$= 2\pi \: Rh + 2\pi \: rh + 2\pi( {R}^{2} - {r}^{2} ) \\ \\ = 2\pi(Rh \: + rh + {R}^{2} - {r}^{2} ) \\ \\ = 2 \times \frac{22}{7} (12.5 \times 20 + 11.5 \times 20 + ( {12.5)}^{2} - ( {11.5)}^{2} ) = \frac{44}{7} (250 + 230 + 156.25 - 132.25) \\ \\ = \frac{44}{7} (480 + 24) \\ \\ = \frac{44}{7} \times 504 \\ \\ = 72 \times 44 \\ \\ = 3168 \: {cm}^{2}$

Hope it helps you.