Question

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From a solid cylinder whose height is 2.4 cm and diameter 1.4 cm, a conical cavity of the

same height and same diameter is hollowed out. Find the total surface area of the

remaining solid to the nearest cm2.​

Answer 1

Answer:

iven :

radius (r)=  

2

diameter

​  

=  

2

1.4

​  

=0.7 cm

height (h)=2.4 cm

Total surface area= surface area of cylinder+ surface area of cone−2(surface area of above circle).

=2πrh+2πr  

2  +πr 2 +πr h  2 +r  

2 −2πr 2 =2πrh+πr h  

2+r  

2 +πr  

2  =π(2rh+r  2+r  h  2 +r  2)

=  7 22  

(2×0.7×2.4+(0.7)  

2 +0.7  

(0.7)  

2  +(24)  2  )

=  7 22

(3.36+0.49+1.75)

=7 22 (5.6)

Total surface area=17.6cm  

2  .

Hence, this is the answer.