Question

From a solid cylinder of height 2.8 cm and diameter 4.2 cm, a conical cavity of the same height and same diameter is hollowed out. Find the total surface area of the remaining solid. (Take $(\pi=\frac{22}{7})$).

Answer 1

Answer:

Total surface area of the remaining solid is 73.92 cm².

Step-by-step explanation:

SOLUTION :  

Given :  

Height of the conical part = Height of the cylindrical part , h = 2.8 cm

Diameter of the cylindrical part = 4.2 cm

Radius of the cylindrical part ,r  = 4.2/2 =  2.1 cm

Slant height,  l = √(h²+ r²)

l = √2.8² + 2.1²

l = √(7.84 + 4.41)

l = √12.25

l = 3.5 cm

Total surface area of the remaining solid   = CSA of cylindrical part + CSA of conical part + Area of cylindrical base

= 2πrh + πrl + πr²

= πr(2h + l + r)

= 22/7 × 2.1(2 × 2.8 + 3.5 + 2.1)

= 22 × 0.3 (5.6 + 5.6)

= 6.6 × 11.2  

= 73.92 cm²

Hence, the total surface area of the remaining solid is 73.92 cm².

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Answer 2

this is the answer....