Question

2. The slant height of a right circular cone is
10 m and its height is 8 m. Find the area of
its curved surface.
A) 30 m2
B) 40 m2
C) 60 m2
D) 80 m2
​

Answer 1

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Given:

The slant height of a right circular cone is 10m and its height is 8m.

To find:

The area of its curved surface area.

Explanation:

We know that formula of the slant height:  l²= r² + h²

We have,

• Slant height of cone,l= 10m
• Height of the cone,h= 8m

→ 10² = r² + 8²

→ 100m² = r² + 64m²

→ r² = 100m² -64m²

→ r² = 36m²

→ r = √36m²

→ r = 6m

We know that formula of the curved surface area of cone: πrl    [sq.units]

→ π × 6m × 10m

→ 60π m²

Thus,

The curved surface area of cone is 60π m².

Answer 2

A N S W E R »

A) 30 m2

B) 40 m2

C) 60 m2 ✓

D) 80 m2

$\bold{\large{\underline{\underline{\sf{StEp\:by\:stEp\:explanation:}}}}}$

The slant height of a right circular cone is 10m and its height is 8m.

To find:

The area of its curved surface area.

By using the formula of the slant height: l²= r² + h²

We have,

Slant height of cone,l= 10m

Height of the cone,h= 8m

→ 10² = r² + 8²

→ 100m² = r² + 64m²

→ r² = 100m² -64m²

→ r² = 36m²

→ r = √36m²

→ r = 6m

We know that formula of the curved surface area of cone: πrl [sq.units]

→ π × 6m × 10m

→ 60π m²