Corresponding sides are a pair of matching sides in two different shapes (size does not matter). In the field of geometry, the concept of corresponding sides plays an important role to prove various triangular theorems.
The Boeing B-17 Flying Fortress is a four-engine heavy bomber aircraft developed in the 1930s for the United States Army Air Corps (USAAC).
United States. USAAC / USAAF was main operator of all versions of the Boeing B-17 Flying Fortress. Most units operating B-17 were based in the European Theatre of World War II but aircraft was used at some point in all theatres of World War II.