Question

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$\underline{A metallic sphere of radius 4.2 cm. is melted and recast into the shape of a cylinder of radius 6 cm. Find the height of the cylinder.}$

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Answer 1

$<b>When a solid is melted to form other solid, its volume remains unchanged. </b>$

So,

Volume of sphere = Volume of Cylinder

4/3 π r^3 = π R^2 h

$\frac{4}{3} \times 4.2\times 4 .2\times 4.2= 6 \times 6 \times h$

296.352/3 = 36 × h

98.784=36 × h

98.784/36 = h

2.744 = h

Or 2.7 cm = h

$\bf{So, \: height\: of cylinder\: = 2.7 cm }$

Answer 2

$\large\sf \: (2x+1)^2=4x^2+1+4x$