Question

the diameter of the laws and supply upper end of bucket in the farm a frustum of a cone are 10 cm and 30 cm respectively. If its height is 24 cm . Find :- the are of the metal short used to make the bucket and the 2. why we should avoid bucket made by ordinary plastic ?

Answer 1

GIVEN :
Diameter of upper end of bucket =30cm
Radius of the upper end of the frustum of cone( r1) = 15cm
Diameter of lower end of bucket = 10 cm
radius of the lower end of the frustum of cone( r2) = 5 cm
H of the frustum of Cone = 24 cm
Slant height of bucket ( L)= √(h² + (r1- r2)²
L =√24² + (15 - 5)² = √576 + 10²
L =√(576+(100)= √676 = 26cm
L = 26 cm
Area of metal sheet require to make bucket = Curved surface Area of frustum + area of base
= π(r1 + r2)L + πr2²
= 3.14(15 + 5) × 26 + π(5)²
= 3.14 × 20 × 26 + 25 × 3.14
= 3.14 (520+ 25)
= 545 × 3.14
= 1711.3 cm²
Hence, the Area of metal sheet used to make the bucket is 1711.3 cm².
2. We should avoid bucket made by ordinary plastic because it is non biodegradable it makes soil less fertile & pollute the environment also.

HOPE THIS WILL HELP YOU...

Answer 2

Solution :-

1) Area of the metal sheet used to make the bucket.

Diameter of the upper end = 30 cm

Radius r1 = 30/2 = 15 cm

Diameter of the lower end = 10 cm 

Radius r2 = 10/2 = 5 cm

Height of the frustum of a cone = 24 cm

Slant height 'l' = √H² + (r1 - r2)²

⇒ √24² + (15 - 5)²

⇒ √576 + (10)²

⇒ √576 + 100

⇒ √676

⇒ l = 26

So, slant height is 26 cm

Total surface area of the frustum of a cone = π(r1+ r2)l + πr2²

⇒ 22/7*(15 + 5)*26 + 22/7*5*5

⇒ (22*20*26)/7 + (22*25)/7

⇒ 11440/7 + 550/7

⇒ 1634.28 cm² + 78.57 cm²

= 1712.85 cm²

So, area of the metal sheet used to make the bucket is 1712.85 cm²

2) We should avoid using buckets made from ordinary plastic because ordinary plastic not biodegradable and makes the fertile soil infertile. Also ordinary plastic is not environment friendly.