Merge pull request #48 from Dick-Lane/master

change tagging for 4 ASU problems that use Law of Sines but do not use Law of Cosines
Merge branch 'master' of github.com:openwebwork/webwork-open-problem-library
Merge pull request #49 from Dick-Lane/master

retag 5 that are not Law of Cosines, fix 1 to have unique solution
Merge branch 'master' of github.com:openwebwork/webwork-open-problem-library
Remove 'Law of Sines' from Keywords because it is not used.