Week #8 Fall 1999  Solution
Win tickets to a Tina Turner concert if when you're rolling
down a river you can solve the WSU Math Department's


MEASURING
THE RIVER

A traveller reaches a river at the point A, and wishes to know the width across to B. As he has no means of crossing the river, what is the easiest way of finding it's width? 
 
Solution:
Measure any convenient distance along the bank from A to C, say 40 yards. Then measure any distance perpendicularly to D, say 12 yards. Now sight along along DB and find the point E. You can then measure the distance  from A to E, which will here be 24 yards, and from E to C, which will be 16 yards. Now AB:DC = AE:EC, from which it is evident that AB, the width of the river, must be 18 yards.