The diameters of the internal and external surfaces of a hollow hemispherical shell are 6cm and 10cm respectively. If it is melted and recast into a solid cylinder of diameter 14cm , find the height of the cylinder .

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Find the area of the shaded region from figure , if the diameter of the circle with centre O is 28cm and AQ = 1/4AB

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Answers

2015-02-10T18:51:15+05:30
1---
  
we have internal diameter =6 and external diameter= 10

therefore

internal radius =3 and external radius =5

now volume of hemisphere=volume of cylinder
4/3π(R³-r³)=πr²h
4/3(98)=49h
therefore

h=8/3cm-----------------ans


2-
now we have diameter=28
then r=14
also we have 
aq=1/4ab
aq=7
therefore
bq=21

now area of shaded figure = sum of two semicircles of diameter 7and 21

= 1/2πr+1/2πR
1/2π(14)
=7cm² -------ans








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