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# Each edge of a regular tetrahedron is 3 cm, then its volume is – A.$9\sqrt3\over4$ $cm^3$ B.$27\sqrt3$ $cm^3$ C.$4\sqrt3\over9$ $cm^3$ D.$9\sqrt3$ $cm^3$

[ A ]    a
[ B ]    b
[ C ]    c
[ D ]    d
 Answer : Option A Explanation : The side of tetrahedron = 3 cm The volume of tetrahedron $\sqrt2a^3\over12$ = $3^3\sqrt2\over12$= $9\over4$ $\sqrt2$ $cm^3$