The model demonstrates tangent and perpendicular to a graph at a point. Consider a function f(x). A tangent to f(x) at a point x_{0} is a line y = f(x_{0})+ f `(x_{0})∙(xx_{0}). A normal to f(x) at the x_{0} is line y = f(x_{0})+(xx_{0})/f `(x_{0}). The normal is a perpendicular to f(x). You may enter a function f(x) in the text field and choose a x_{0}. The y_{0}=f(x_{0}), tangent and normal at this point are calculated automatically in analytical form. The graph of the f(x) is blue, the tangent is a green line, the normal is a red line.
