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atjari
Can sum1 answer this with explanation pls?
see now initially the origin in O and lets shift the origin to O'. Now imagine that O wrt O' is r'. Hence now the vector coordinates in new coordinate system would be (r1 + r'), (r2 + r'), (r3 + r1), (r4 + r'). For the equation to hold a1 * (r1 + r') + a2 *(r2 + r') + a3*(r3 + r') + a4*(r4 + r') = 0 (we need to find the condition for this to hold) the equation reduces to (a1*r' + a2*r' + a3*r' + a4*r') +( a1r1 + a2r2 + a3r3 + a4r4) sum in the second paranthesis is zero (given) . Hence for eqn to hold = r'*(a1 + a2+ a3+ a4) = 0 or a1 + a2 + a3 + a4 = 0 hence proved..
in if and only if you have to prove both ways .. but given this proof the revers is easy as well .. hope m clear...
Ya. I'm clear nw. Thanx a lot.