Determine the equation of the line perpendicular to the tangent line to the function f(x) = 1/2 (e^x)at the point on the curve where x=ln3.

f '(x) = (1/2)e^x

sub in x = ln3 and you will have the slope
find y when x = ln3

so now you have the slope and a point, use your
y = mx + b method to find the tangent.