Question

if P1,P2,P3,P4 are points in a plane and O is the origin of vector show that P4 coincide with O if and only iff OP1+P1P2+P2P3+P3P4=0​

Answer 1

OP1+P1P2+P2P3+P3P4=0

GROUPING

(OP1+P1P2)+(P2P3+P3P4)=0

if (OP2)+(P2P4)=0                                      {BY TRRIANGLE LAW}

if OP4=0                                                       { again BY TRIANGLE LAW}

if O and P4 coincides

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