A rectangular box has length 19 inches, width 13 inches, and a height of 6 inches. find the angle between the diagonal of of the box and the diagonal of its base. the angle should be measured in radians.

In this case you have to use a graphing calculator for radians. But you're going to use either sine or cosine and remember since its a box you automatically have a 90° angle to work with. it may be a 30°, 60°,90°or a 45°, 45°, 90° triangle