Problem:
In the adjoining figure, is a diagonal of the cube. If has length , then the surface area of the cube is
Answer Choices:
A.
B.
C.
D.
E.
Solution:
Let be the length of an edge of the cube, and let and be vertices of the cube as shown in the adjoining figure. Then applying the Pythagorean theorem to and yields
.
The surface area is .
