Question

find the total surface area of a cone, if it's slant height is 9 m and the radius of its base is 12 m​

Answer 1

Given:

• Slant height of cone, l = 9 m
• Radius of cone, r = 12 m

To find:

• Total surface area of the cone ?

Solution:

As we know that,

⋆ TSA of cone = πr(r + l)

Putting the values,

➜ 22/7 × 12(12 + 9)

➜ 264/7 × 21

➜ 792 m² (approx)

Therefore, TSA of cone is 792 m².

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Answer 2

Given

• Slant height of cone=9m
• Radius of cone=12m

To Find

• Total surface area of cone

Concept used

• $\rm \:tsa \: of \: cone = \pi \: r(l + r)$

Solution

We have the height and radius of cone

therefore we directly put values in the formula to get our answer.

Here we have

• Slant height (l)=9m
• Radius of base (r)=12m

Putting values we get

$\rm \: tsa \: of \: cone = \pi r(l + r) \\ \\ \implies \rm \: tsa = \frac{22}{7} \times 12(9 + 12) \\ \\ \implies \rm \boxed{ \bf tsa = 792 \: {m}^{2} } \: \: \: \: \: \: \: \:$

So the tsa of cone is 792m²

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