A rectangular metal block has length 15cm ,breadth 10cm and height 5cm. From this block a circular hole of diameter 7cm is drilled out find :

(a)the volume of the remaining solid

(b)the surface area of remaining solid

(i) the length , breadth and height of the metal block is 15 cm , 10 cm and 5 cm respectively.

therefore the volume of the rectangular block is 15*10*5=750 cubic cm

the diameter of the circular hole is 7 cm.

therefore the radius of the circular hole is 7/2=3.5 cm

the height of the circular hole will be equal to the height of the rectangular block i.e. 5 cm

the volume of the circular hole =

 

the volume of the remaining solid = volume of the rectangular block - volume of the circular hole

=750-192.5

=557.5 cubic cm


(ii)

the total surface area of the remaining solid 

= surface area of the rectangular block - 2 *area of the circle of the hole + area of the curved surface of the hole (cylinder)

=  [where l , b and h are the length , breadth and height of the rectangular block and r is the radius of the circular hole.

hope this helps you.

cheers!!

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