Let the complex number z1,z2,z3 be the varticles of an equilateral triangle . let z0 be the cirumcental of the triangle . prove that z12+z22+z32=3z20
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Solution
let the vertices of the triangleABC be represented by z1,z2,z3 then by the rotation in anti clock about A , B , we get AC=ABeπi/3,,BA=ACeπi/3, (z3−z1)=(z2−z1)eπi/3(z1−z2)=(z3−z2)eπi/3 z3−z1z2−z1=z2−z1z3−z1[z3−z1][z2−z1]=[z2−z1]2orz12+z22+z32=z1z2+z2z3+z3z1Now for the an equiliteral traingle , circumceral is the same as the centrid so that z0=z1+z2+z3=/3or9z09=z12+z22+z32z1z2+z2z3+z3z1=2z1z2+2z2z3+2z3z1