Find the smallest positive value for `theta` for which the tangent line to the curve `r = 6 e^(0.4 theta)` is horizontal
The Attempt at a Solution
I tried to use the (r'sin(theta)+rcos(theta))/(r'cos(theta) - rsin(theta)) formula to get the tangent line, which I got to be...
And then find the theta that would make this equation 0, got pi/2, but the answer is 1.95130270391. Help?