Question

calculate the outer surface area of a hollow cube of side 15 CM which has circular holes of radius 3.5 CM on all six sides​

Answer 1

Answer:

$1276.5 \:cm^2$

Step-by-step explanation:

First of all we are going to find the area of each face of cube.

Secondly we are going to find the area of the circle on each face.

Thirdly, we'll subtract the total area of circles on all the six faces from the total area of cube.

$Area\:of\:each\:face\:=\:15\times 15\:=\:225\:cm^2\\Total\:Surface\:area\:of\:cube\:=\:6\times 225\:=\:1350\:cm^2\\Area\:of\:circle\:on\:each\:face\:=\:3.5\times \:3.5\:=\:12.25\:cm^2\\Total\:Surface\:area\:of\:all\:the\:circles\:on\:cube\:=\:6\times 12.25\:=\:73.5\:cm^2\\\\\\Outer\:Surface\:Area\:of\:Cube\:excluding\:the\:circles\:=\:1350-73.5\:=\:1276.5\:cm^2$

Answer 2

Answer:

area of cube =(6×15×15)

=1350cm^2

area of 6 circles on 6 faces=6×π×r^2

=6×π×3.5^2

=231cm^2

now outer surface area=area of cube-area of 6 circles

=1350-231=1119 cm^2