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Show that veca.(vecbxxvec c) is equal in magnitude to the volume of the parallelopiped formed on the three vectors, veca,vecb and vec c |
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Answer» Solution :Suppose `VEC(OA)=vecb,vec(OC)=vecc and vec(OE)=VECA` `vecb and vec c` are adjacent sides of parallelogram OABC Area of `squareOABC,vecS=vecbxxvecc` `:.Shatn=vecbxxvecc` where `HATN` unit vector perpendicular to plane form by `vecb and vecc and theta` is angle between `veca and vecS`. `:.veca.(vecbxxvecc)=veca.vecS [because vecbxxvecc=vecS]` `=aScostheta` `=(acostheta)S` `=hS""......(1)` where in `DeltaEOE., EE.=h=acostheta` Suppose VOLUME of parallelepiped OABCDEF is V. `:.V` = Area of `squareOABCxx` perpendicular (h) of parallelogram OABC from E `:. V=sh"".....(2)` From result (1) and (2) `veca.(vecbxxvecc)=V` |
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