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Curved surface area of a cone is 251.2 cm2 and radius of its base is 8 cm. Find its slant height and perpendicular height. (π = 3.14) - Geometry

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प्रश्न

Curved surface area of a cone is 251.2 cm2 and radius of its base is 8 cm. Find its slant height and perpendicular height. (π = 3.14)

योग

उत्तर

Let the perpendicular height and slant height of the cone be h cm and l cm, respectively.

Radius of the base of cone, r = 8 cm
Curved surface area of the cone = 251.2 cm2

∴ πrl = 251.2 cm2

⇒ 3.14 x 8 x l = 251.2

⇒ l = `251.2/25.12` = 10 cm

Now,

r2 + h2 = l2

⇒ (8)2 + h2 = (10)2

⇒ 64 + h2 = 100 

⇒ h2 = 100 - 64 = 36

⇒ h = `sqrt36` = 6 cm

Thus, the slant height and perpendicular height of the cone are 10 cm and 6 cm, respectively.

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अध्याय 9: Surface Area and Volume - Practice Set 9.2 [पृष्ठ ११९]

APPEARS IN

बालभारती Geometry (Mathematics 2) [English] 9 Standard Maharashtra State Board
अध्याय 9 Surface Area and Volume
Practice Set 9.2 | Q 3. | पृष्ठ ११९

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