\[\frac{r \cdot \sin b}{\color{red}{\cos \left(a + b\right)}} \leadsto \frac{r \cdot \sin b}{\color{blue}{\cos a \cdot \cos b - \sin a \cdot \sin b}}\]
0.3
Using strategy rm
0.3
Applied associate-/l* to get
\[\color{red}{\frac{r \cdot \sin b}{\cos a \cdot \cos b - \sin a \cdot \sin b}} \leadsto \color{blue}{\frac{r}{\frac{\cos a \cdot \cos b - \sin a \cdot \sin b}{\sin b}}}\]
0.4
Applied simplify to get
\[\frac{r}{\color{red}{\frac{\cos a \cdot \cos b - \sin a \cdot \sin b}{\sin b}}} \leadsto \frac{r}{\color{blue}{\frac{\cos a}{\frac{\sin b}{\cos b}} - \sin a}}\]
0.4
Removed slow pow expressions
Original test:
(lambda ((r default) (a default) (b default))
#:name "r*sin(b)/cos(a+b), A"
(/ (* r (sin b)) (cos (+ a b))))