On a clear day, you can see 11.5 km in any direction from a particular lookout. If a straight road is 6.9 km from the lookout, what length of the road can be seen from the lookout?

Answer 1

Draw a diagram. You have a circle of radius 11.5, and a chord 6.9 from the center.
If the length of road is 2x, then

6.9^2 + x^2 = 11.5^2
find x, then 2x

Answer 2

4.6 km