The Equation of Tangents and Normals, If you differentiate the equation of a curve, you will get a formula for the gradient of the curve. Are you working to find the equation of a tangent line (or normal line) in Calculus? The derivative of a function at a point is the slope of the tangent line at this point. The normal line is defined as the line that is perpendicular to the tangent line at the point of tangency.

Equation of tangent and Normal

Tangent and Normal