Girls in Math at Yale 2022 Mathathon Round 4
Source:
March 7, 2022
logarithmsalgebrageometrycombinatoricsnumber theoryYale
Problem Statement
p10 Kathy has two positive real numbers, and . She mistakenly writes
but miraculously, she finds that for her combination of and , the equality holds. If , then , for positive integers where . Find .
p11 Points and lie on sides and of triangle , respectively. Ray is extended to point such that , and are collinear, in that order. If triangle is isosceles and triangle is equilateral, then the possible values of lie in the interval , such that and such that is as large as possible and is as small as possible. Find .
p12 Let and are integers . In other words, is the set of points in the coordinate plane with integer coordinates between and , inclusive. Prair selects four distinct points in , for each selected point, she draws lines with slope and slope passing through that point. Given that each point in lies on at least one line Prair drew, how many ways could she have selected those four points?