Strategies and Hints

1. This figure is better for solving the problem because it shows the angle the mirror makes with the wall.

2. The problem asks for the angle the mirror makes with the wall. In this figure, that angle is .

3. Neither Student A nor Student B will be able to solve the problem because, without knowing the width of the mirror, there is no way to find the height of the triangle formed by the wire. Student C has interpreted the problem in an interesting way. But, since the problem gives no information about the angle the wire forms with the top of the picture, Student C will be unable to determine angle W.
   
   There is, of course, nothing "wrong" with the interpretations of Students A, B, and C. However, if one assumes that a unique solution exists, it is a goal to interpret the problem so that such a solution may be found.

Solution

Using the Law of Cosines:

cos =

= 8.568°