Question

An oblong measures 15 cm by 8 cm. find the angle between its diagonal and a longer edge answer

Answer 1

For this case you can model the problem as a rectangle triangle where you have the length of the opposite leg and the adjacent leg.
 Therefore, the angle sought is given by:
 theta = Atan (8/15)
 theta = 28.07 degrees
 Answer: 
 The angle between its diagonal and a longer edge is: 
 theta = 28.07 degrees