A hemispherical depression of diameter 4 cm is cut out from each face of a cubical block of sides 10 cm. Find the surface area of the remaining solid (in cm2)
(Use π=$\frac{22}{7}$)
Answer & explanation
Correct answer: option 3
We know that,
TSA of the cube = 6a2
CSA of the hemisphere = 2πr2
Area of a circle = πr2
We have,
Diameter of the hemispherical depression = 4 cm
Each face of the cube = 10 cm
Then the radius of hemisphere = 5
Required surface area = TSA of the cube - 6 × areas of circle form on the top of each face of the cube + 6 × CSA of hemisphere formed on each face of a cube
= 6 × 102 - 6 × π22 + 6 × 2π22
= 600 + 6π22
= 600 + 24 × \(\frac{22}{7}\) = 600 + \(\frac{528}{7}\) = $675\frac{3}{7}$