Question

7. Curved surface area of a cone is 308cm’ and its slant height is 14cm. find (i) Radius of the base and (ii) total surface area
of the cone. (Use pi=22/7)​

Answer 1

Step-by-step explanation:

we know that ,

l = 14cm , r = 7cm

Total surface area of cone = Πr(l+r)

= 22/7 ×7 × (14+7)

= 22/7 × 7 × 21

= 22 ×1 × 21

= 462 cm²

Therefore , the total surface area of the cone is 462cm²

Answer 2

Given:

→ curve surface area of cone= 308 cm²

→ slant height = l = 14cm

Solution:-

(i) radius of the base

→ curved surface area of cone = πrl

→ πrl = 308

$→ \frac{22}{7} \times r \times 14 = 308$

$→r = \frac{308 \times 7}{22 \times 14}$

$→r = 7cm$

Hence, the radius of the base is 7 cm

(ii) total surface area of cone

→ total surface area of cone = π r(l +r)

$→ \frac{22}{ 7} \times 7 \times (14 + 7)$

$→22 \times 21$

$→462 \: {cm}^{2}$

Hence,Total surface area of cone = 462 cm²