calculus
posted by Daniel .
Find an equation of the tangent line to the curve at
y = cosx  sinx (pi, 1)
I found y'= sinx  cosx
and used the equation of the tangent
y = mx +b
I input the values and get 1  [(sinx  cosx) * pi] = b
the answer says it is y = x  1  pi
I have no idea how the answer got that.

m= sinPIcosPI=1
y= x+b
1=PI+b
b= PI1
y=xpi1