Question

The circumference of the base of a right circular cone is 220 cmQ and its height 84cm.the curved surved surface area of the cone is ??

Answer 1

Given :-

circumference of the base of the cone = 220cm

we know that, 2πr = circumference

➡ 2πr = 220cm

➡ 2 × 22/7 × r = 220cm

➡ r = 220/2 × 7/22

➡ r = 70/2

➡ r = 35cm

the radius of the cone is 35cm

height of the cone is is given = 84cm

here, we've to find the lateral surface area of the cone.

formula to find it's lateral surface area is πrl where l is the slant height of the cone.

by Pythagoras theorem, we get

➡ l² = r² + h²

➡ l² = 35² + 84²

➡ l = √(1225 + 7056)

➡ l = √8281

➡ l = 91cm

hence, the lateral surface area of the cone = πrl

= 22/7 × 35 × 91

= 22 × 5 × 91

= 10010cm² final answer

Answer 2

$\huge{\underline{\mathfrak{</p><p><strong>Answer:</strong></p><p>}}}$

Given :-

The circumference of right circular cone is 220 cm.

We know that,

$\huge{\boxed{Circumference\:\: of\:\: cone = 2πr}}$

» 2πr = 220 cm

» 2 × 22/7 × r = 220

» r = 70/2

» r = 35 cm

$\rule{200}{2}$

» l² = h² + r²

» l² = 84² + 35²

» l² = 7056 + 1225

» l = √8281

» l = 91 cm

We know that

$\huge{\boxed{CSA\:\: of\:\: cone = πrl}}$

» 22/7 × 35 ×91

» 22 × 5 × 91

» 10010 cm²

Hence, the lateral surface area of cone is 10010 cm²