Question 19
If $x=\sin\alpha$, $y=\sin\beta$ and $z=\sin(\alpha+\beta)$, find $\cos(\alpha+\beta)$.
Domain for this self-study question: x and y are both nonzero. Compare the options as identities valid throughout this domain. The source omits this restriction although its options contain denominators x or xy.
Domain for this self-study question: x and y are both nonzero. Compare the options as identities valid throughout this domain. The source omits this restriction although its options contain denominators x or xy.