What are the sides of the rectangular prisms ?
Exterior angles are found along the outside of the figure if you extend the figure's side lengths.
The exterior angles in the image would be 4 and 5.
6 isn't an angle, and all of the other options are found on the inside of the triangle (1,2 and 3).
It's not possible to know, because you're not letting us see
the accompanying right triangle.
