Hey Mike, I have a question concerning an example problem in the PWN SAT Guide, 4th edition. On p. 280 in the Working in 3-D chapter (Example 3), it says that a right triangle was formed by the dotted lines in the cube. I’m kind of confused because the dotted lines don’t seem to contain a right angle.

Thanks for asking this!

The dotted lines and the edge of the cube don’t appear to form a right triangle in the figure because of the orientation of the cube, but that is indeed a right triangle. If you follow the edge of the cube up from point *A* to the top corner, and then you head towards point *B*, you must make a 90° turn.

If you could reorient the cube so that you were looking straight at the triangle, it would be more clear. The triangle in 2-D looks like this: