The tangent As a tangent is a straight line it is described by an equation in the form y b = m (x a). You need both a point and the gradient to find its equation.

How to Find the Tangent on a Graph in Excel. The tangent is defined as the single point where a straight line meets a curved surface.

Simultaneous equations, where one of the graphs is quadratic and the other is a straight line, can be solved by reading the points of intersection ...