Betty decides to compare the diagonals of both the square and rectangular tables customers will use in the coffee shop. Her measurements show that the square tables have a side length of 34 inches and the rectangular tables are 29 1/ 3 inches wide and 35 inches long. She uses the formula d i a g o n a l (width Square root)^2 + (h e i g h t)^2 to compute the diagonal of each table.

Which table has a diagonal whose length (measured in inches) is an irrational number? What is the length of this diagonal?

1 answer

sqrt (34^2 + 34^2)
= sqrt [(2*17)^2 + (2*17)^2]
= sqrt [ 4*17^2 + 4*17^2)]
=2 * sqrt (2*17^2)
= 34 sqrt 2 which is irrational

sqrt [(29 1/3)^2 + 35^2 ]
sqrt [ (88/3)^2 + 35^2 ]
sqrt [ 7744/9 + 1225 ]
sqrt [ 7744/9 + 11025/9 ]
sqrt [ 18769/9 ]
(1/3) sqrt (18769)
(1/3)(137)
= 137/3 which is rational