Two vertical poles, 11 m and 6 m tall, stand on level ground 12 m apart. How far is the top of one pole from the top of the other?

Explanation

1. 01

   Join the tops. Drop a horizontal line from the top of the shorter pole to the taller pole: it is 12 m long and meets the taller pole $11 - 6 = 5$ m below its top.

2. 02

   Distance between tops = $\sqrt{12^2 + 5^2} = \sqrt{169} = 13$ m.