The volume of a paper cone of radius 2.4cm is 95.4 cm3.

The paper is cut along the slant height from O to AB.

The cone is opened to form a sector OAB of a circle with centre O.

Calculate the sector angle x°.

[The volume, V, of a cone with radius r and height h is V= 1/3 x π x r² x h.]

Respuesta :

The sector angle formed by the cone when it is opened is: 54°.

What is the Curved Surface Area of a Cone?

Curved surface area of a cone = πrl, where l is the slant height and r is the radius of the cone.

What is the Area of Sector?

Area of a sector in a circle = ∅/360 × πr², where ∅ is the sector angle.

Step 1: Find the height (h) of the cone using the volume formula, V= 1/3 x π x r² x h:

V = 95.4 cm³

r = 2.4 cm

Plug in the values:

95.4 = 1/3 x 3.14 x 2.4² x h

95.4 = 6.03 x h

h = 15.8 cm

Step 2: Use the pythagroean theorem to find the slant height (l) of the cone

l = √(h² + r²)

Plug in the values

l = √(15.8² + 2.4²)

l = 16 cm.

Step 3: Find the curved surface area of the cone

Curved surface area = πrl = π(2.4)(16) = 120.6 cm².

Step 4: Find the sector angle of the sector formed by the cone when opened

Curved surface area of the cone = area of the sector formed by the cone = 120.6 cm².

Area of a sector in a circle = ∅/360 × πr², therefore:

120.6 = ∅/360 × (3.14)(16²)

120.6 = ∅/360 × 803.84

(120.6)(360) = (∅)(803.84)

43,416 = (∅)(803.84)

43,416/803.84 = ∅

∅ = 54°

Therefore, the sector angle formed by the cone when it is opened is: 54°.

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