Question

find the equation of the tangent line at the point specified..
y = xtanx ; x = pi/4

Answer 1

y = f'(pi/4)x -(pi/4)*f'(pi/4) + f(pi/4)

Answer 2

say x=c for simplicity, then we know the derivative IS the slope at c
\[y=f'(c)x-c*f'(c)+f(c)\]

Answer 3

yes but isnt tanx' = sinx/cosx and dont i then have to find the derivative of that?