A tangent line is a straight line that touches a function at only one point. The slope of the tangent line (the gradient) at a point on the function is equal to the derivative of the function at the same point.

. At , The tangent gradient equals

Equation of tangent:

The equation of Normal line has the same coordinate of intersection and the same y-intercept but the gradient is different. The gradient of the normal line is where is the gradient of the tangent line and is the gradient of the normal line.

This Equation of normal line: