MathDB
Trigonometry makes rational number

Source: All-Russian MO 2023 Final stage 11.1

April 23, 2023
trigonometryquadratics

Problem Statement

If xRx\in\mathbb{R} satisfy sinsin x+tanx+tan xQx\in\mathbb{Q}, coscos x+cotx+cot xQx\in\mathbb{Q} Prove that sinsin 2x2x is a root of an integral coefficient quadratic function