Exercise 25 Page 385

Before we begin, note that $A$ is the intersection of $B D$ and $C E .$ For two rays to be opposite, they must have the same endpoint and point in opposite directions. The rays $A D$ and $A C$ have the same endpoint, $A,$ but they do not point in opposite directions. Highlighting the rays in the diagram makes this easier to see.

To fix this error, we need to make sure the two rays are opposite. One solution would be to exchange $A D$ for $A E .$ This gives us the opposite rays $A C$ and $A E .$

We could, similarly, create the opposite rays $A B$ and $A D .$