MathDB
tangents form equilateral triangle

Source: VJIMC 2004 1.1

July 2, 2021
geometryfunctioncalculus

Problem Statement

Suppose that f:[0,1]Rf:[0,1]\to\mathbb R is a continuously differentiable function such that f(0)=f(1)=0f(0)=f(1)=0 and f(a)=3f(a)=\sqrt3 for some a(0,1)a\in(0,1). Prove that there exist two tangents to the graph of ff that form an equilateral triangle with an appropriate segment of the xx-axis.