the height, curved surface area and volume of a cone are H, C and V respectively Prove that: 3pie v h sq - c sq h sq + 9v sq =0
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The curved surface area of a cone
=C
=πrl
=πr√(h²+r²)
where h, l and r are the height, slant height and radius of the cone.
Volume of the cone
=V
=πr²h/3
∴3πVh³-C²h²+9V²
=3π{(πr²h)/3}h³-{πr√(h²+r²)}²h²+9(πr²h/3)²
=π²r²h⁴-π²r²(h²+r²)h²+9π²r⁴h²/9
=π²r²h⁴-π²r²h⁴-π²r⁴h²+π²r⁴h²
=0 (Proved)
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