Exercise 3 Page 347

To fit tightly on the nut, the shape and size of the opening of the socket should be the same as the shape and size of the nut. The hexagonal nut should be congruent to the hexagonal opening of the socket.

Both the nut and the opening of all sockets are regular hexagons, so the angles are congruent. However, only the 1/2 inch socket matches the side length. The 3/8 inch socket is too small, and the other sockets are too large.