The distance between Saurabh's college and the library. Applying Pythagoras Theorem Shortest distance 2= Vertical distance 2+ Horizontal distance 2 AC2=AB2+BC2 =(20)2+(15−10+16)2 =(20)2+(21)2 =400+441 =841 =292 Shortest distance =29km Hence, the shortest distance between Saurabh's college and library is 29 km .