Question

Find the total surface area of a cone, if its slant height is $$21\ cm$$ and diameter of its base is $$24\ m$$.

Answer 1

It is given that

Diameter of the cone $$=24\ m$$

Radius of the cone $$=\dfrac{24}{2}=12\ m$$

Slant height of the cone $$=21\ cm$$

We know that

Total surface area of a cone $$=\pi r(1+r)$$

By substituting the values

Total surface area of a cone $$=\dfrac{22}{7}\times 12(21+12)$$

On further calculation

Total surface area of a cone $$=\dfrac{22}{7}\times 12\times 33$$

So we get

Total surface area of a cone $$=1244.57\ m^{2}$$

Therefore, the total surface area of a cone is $$1244.57\ m^{2}$$