MathDB
shape in complex plane

Source: LIMIT 2019 CAS1 P9

April 28, 2021
complex numberscomplexalgebrageometry

Problem Statement

ABCDABCD is a quadrilateral on the complex plane whose four vertices satisfy z4+z3+z2+z+1=0z^4+z^3+z^2+z+1=0. Then ABCDABCD is a <spanclass=latexbold>(A)</span> Rectangle<span class='latex-bold'>(A)</span>~\text{Rectangle} <spanclass=latexbold>(B)</span> Rhombus<span class='latex-bold'>(B)</span>~\text{Rhombus} <spanclass=latexbold>(C)</span> Isosceles Trapezium<span class='latex-bold'>(C)</span>~\text{Isosceles Trapezium} <spanclass=latexbold>(D)</span> Square<span class='latex-bold'>(D)</span>~\text{Square}