Who knows? Not having any other information than the measures of two sides of a triangle, you can only tell that the third side must be larger than the difference between the two given measures and smaller than the sum of the two measures. Therefore if the two sides are 16 and 20 km, then the measure of the third side, denoted by , must fall in the interval:
Now, if you had a right triangle and the two legs were 16 and 20, the hypotenuse would be 25. But a right triangle where one of the legs is 16 and the hypotenuse is 20 has a third side that measures 12. But the way you worded the problem, you can't tell whether the triangle is even a right triangle or not.
