Question

The curved surface area of a cone is 204.1cm^2 and its radius is 5 cm what is its height

Answer 1

❏ Given that :-

1. C.S.A of cone = 204.1 cm²
2. Radius of cone = 5 cm

❏ To find :-

1. Height of cone .

❏ Solution :-

C.S.A of cone = πrl

{ r = radius of cone ; l = slant height of cone }

but given that CSA = 204.1 cm²

.°. π ×r × l = 204 .1

3.14 × 5 × l = 204.1

$l \: = \: \frac{204.1}{3.14 \times 5}$

l = 13 cm

Now , as we know that l²= h² + r²

→l² = h² + r²

→13² = h² + 5²

→h² = 169 - 25

→h² = 144

→h = 12 cm

Hence height of cone is 12 cm

❏ Formulae :-

Slant height of cone = {√h²+r²}

CSA of cone = πrl

TSA of cone = πr ( l+r )

Volume of cone = πr²h /3