f(x) = log(x)
M = Point(f)
O = Intersect(xAxis, yAxis)
a = Segment(O, M)
OM = Distance(O, M)
T = Tangent(M, f)
g(x) = exp(x)
b: y = x
M' = Mirror(M, b)
c = Segment(O, M')
d = Tangent(M', g)