2002 USA TST Problems
Problems from the 2002 USA TST.
Contents
[hide]Day 1
Problem 1
Let be a triangle. Prove that
Problem 2
Let be a prime number greater than 5. For any integer , define
.
Prove that for all positive integers and the numerator of , when written in lowest terms, is divisible by .
Problem 3
Let be an integer greater than 2, and distinct points in the plane. Let denote the union of all segments . Determine if it is always possible to find points and in such that (segment can lie on line ) and , where (1) ; (2) .
Day 2
Problem 4
Let be a positive integer and let be a set of elements. Let be a function from the set of two-element subsets of to . Assume that for any elements of , one of is equal to the sum of the other two. Show that there exist in such that are all equal to 0.
Problem 5
Consider the family of nonisoceles triangles satisfying the property . Points and lie on side such that and . Point is in the plane such that is the incenter of triangle . Prove that exactly one of the ratios
is constant (i.e., it is the same for all triangles in the family).
Problem 6
Find in explicit form all ordered pairs of positive integers such that divides .