A student begins a proof of the law of cosines. His work is shown.
The next step in the proof is to write an expression for the length of side AZ in terms of
.
Then the student should write an expression for the length of side AY in terms of
.
Next he can use the
![A student begins a proof of the law of cosines His work is shown The next step in the proof is to write an expression for the length of side AZ in terms of Then class=](https://us-static.z-dn.net/files/d24/629216f32959646fca3f0c23f5e06d79.png)