NOTE: This has an exponent which is variable. We cannot use our formula
`d/dx x^n=nx^(n-1)`
from before.
Now
`ln\ y=ln[(sin x)^x]=x\ ln(sin x)`
So
`1/y(dy)/(dx)=x(cos\ x)/(sin\ x)+ln(sin\ x)(1)`
`{: ( (dy)/(dx),=y(x\ cot\ x+ln(sin\ x))),(,=(sin\ x)^x(x\ cot\ x+ln(sin\ x))) :}`