Art of Problem Solving

1983 USAMO: Difference between revisions

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==Problem 1==
==Problem 1==


  If six points are chosen sequentially at random on the circumference of a circle, what is the probability that the triangle formed by the first three is disjoint from that formed by the second three? <math>3</math>
  If six points are chosen sequentially at random on the circumference of a circle, what is the probability that the triangle formed by the first three is disjoint from that formed by the second three?


==Problem 2==
==Problem 2==

Revision as of 18:05, 13 November 2011

1983 USAMO Problems

Problem 1

If six points are chosen sequentially at random on the circumference of a circle, what is the probability that the triangle formed by the first three is disjoint from that formed by the second three?

Problem 2

Prove that the zeros of

\[x^5+ax^4+bx^3+cx^2+dx+e=0\]

cannot all be real if $2a^2<5b$.