MathDB
Broken Tripod

Source: 2006 AIME A Problem 14

March 9, 2006
floor functiongeometry3D geometrypyramidsymmetrytrigonometrytetrahedron

Problem Statement

A tripod has three legs each of length 5 feet. When the tripod is set up, the angle between any pair of legs is equal to the angle between any other pair, and the top of the tripod is 4 feet from the ground. In setting up the tripod, the lower 1 foot of one leg breaks off. Let hh be the height in feet of the top of the tripod from the ground when the broken tripod is set up. Then hh can be written in the form mn,\frac m{\sqrt{n}}, where mm and nn are positive integers and nn is not divisible by the square of any prime. Find m+n.\lfloor m+\sqrt{n}\rfloor. (The notation x\lfloor x\rfloor denotes the greatest integer that is less than or equal to xx.)