A cone of height 8m has a curved surface area 188.4 square meters. Find it volume
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Given, height of cone, h = 8 m
Let r be radius and l be slant height of cone,
Given, curved surface are of cone = 188.4 m2
⇒ πrl = 188.4

On squaring both sides, we get

r4 + 100 r2-36r2 -3600 = 0
r2(r2 + 100) -36 (r2 + 100) = 0
(r2-36)(r2+100) = 0
⇒ r2 = 36, -100
r2 ≠ -100
⇒ r2 = 36
or r = 6 cm
Hence radius is 6 cm.

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Let r be radius and l be slant height of cone,
Given, curved surface are of cone = 188.4 m2
⇒ πrl = 188.4

On squaring both sides, we get

r4 + 100 r2-36r2 -3600 = 0
r2(r2 + 100) -36 (r2 + 100) = 0
(r2-36)(r2+100) = 0
⇒ r2 = 36, -100
r2 ≠ -100
⇒ r2 = 36
or r = 6 cm
Hence radius is 6 cm.

check
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