## Algebra and Trigonometry 10th Edition

a) We see that $\sin u =\sin v =x$. It is a positive number. and $\sin (u+v)=0$ Thus, $x+x \ne 0$ so, $2x \ne 0$ We see that $\sin u =\sin v =x$, and it is a positive number. and $\sin (u-v)=-1$ Thus, $x-x \ne -1$ so, $0 \ne -1$