mathematics geometry question. triangle abc

Answer:
This will be s - r.
Step-by-step explanation:
Here,
SinB = r
CosB = s
SinB = AC/BC
Also,
CosC = AC/ BC
So, we can say SinB = CosC = r
Again,
CosB = AB/ BC
Also,
SinC = AB/ BC
So,
CosB= SinC = s
So,
SinC - CosC = s - r