A cube whose edge is 21 cm long has a circle
of diameter 21 cm on each of its faces painted
black. What is the total area of the unpainted
surface of the cube?
Answers
Answer:
first find the area of just one side of a cube and circle
area of spuarebecause a side of cube is square=l^2
=21×21=441=a1
area of a circle=22/7×21×21=1386=a2
:.unpainted area of one side=a2-a1
=1386-441=945=a3
:. area(unpainted)=a3×6......(6 sides of a cube)
945×6=5670sq.cm
Answer:cube edge =21cm (given)
Diameter,d =21 cm(given)
therefore,
Radius ,r =21÷2=10.5 cm
total surface area of cube = 6 ×21²cm =6×440cm
=2646cm
now,
area of the circle =6( 22/7× r²) =2077.1 1cm
total unpainted area= tsa of cube- 6(area of circle)
=2646-2077.11 =568.89cm² -ans.
hope it helps you friend
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