Question

What angle does the tangent to the curve y(x)=sin^2(x/9)+16sin(x/9) at x=9\pi make with the x-axis?

Answer 1

if y' is slope, then slope is the tangent of that angle.

y'=2sin( )cos( ) + 16cos( )

at x/9, compute all that, then the angle is

arctan(y')