Discussion

Explanation:

The area of the copper sheet required to prepare a cone of base radius 30 cm and height 40 cm will be equal to the total surface area of the cone.

Total Surface area of cone = π × r(r + l) 

Where l is the slant height of the cone and r is the radius of its base.

Also, l =$\sqrt{{\mathrm{r}}^2+{\mathrm{h}}^2}$

∴ Using r = 30 and h = 40, we get l = 50 cm

∴ Total Surface area of cone = 22/7 × 30 × (30 + 50) ≈ 7543 cm²

Hence, option (a).

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