MathDB
triangle ruler construction, equal area trapezoid (2011 Kyiv City MO 10.3)

Source:

July 14, 2020
geometrytrapezoidconstructionRulerTriangle

Problem Statement

A trapezoid ABCDABCD with bases BC=aBC = a and AD=2aAD = 2a is drawn on the plane. Using only with a ruler, construct a triangle whose area is equal to the area of the trapezoid. With the help of a ruler you can draw straight lines through two known points.
(Rozhkova Maria)