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Randy has a cube with an edge of 21 cm. From in the middle of one face of this cube Randy cuts out and removes a cube with an edge of 3 cm. Find the change in surface area of the original cube.

 Oct 15, 2020
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Randy has a cube with an edge of a = 21 cm. From in the middle of one face of this cube Randy cuts out and removes a cube with an edge of b = 3 cm. Find the change in surface area of the original cube.

 

Hello Guest!

 

\(S_1=6a^2=6\cdot (21cm)^2\)

\(S_1=2646cm^2\)

 

\(\Delta S=-b^2+5b^2=4b^2=4\cdot (3cm)^2\)

\(\Delta S=36cm^2\)

 

\(The\ cube\ changes\ its\ Surface\ by\ 36\ cm ^ 2.\)

 

\(S_2=S_1+\Delta S=2646cm^2+36cm^2\)

\(S_2=2682cm^2\)

laugh  !

 
 Oct 15, 2020

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