The decorative block is made of two solids a cube and a hemisphere. The base of the block is a cube with edge 5 cm, and the hemisphere fixed on the top has a diameter of 4.2 cm. Find the total surface area of the block.

Answer

`163. 86 cm^2 `

Explanation

Edge of the cube a= 5 cm.
Radius of the hemisphere, `r=(4.2 )/(2) cm= 2.1 cm `
Total area to be painted
= total surfcae area of the cube - base area of the hemisphere + curved surface area of the hemisphere
`= 6a^2-pi r^2 + 2pi r^2 = 6a^2 + pir^2 `
`=(6xx 5 xx 5 +22/7 xx 2.1 xx 2.1 ) cm^2`
`= (150 + 13.86 ) cm^2 = 163. 86 cm^2 `
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