A normal line is a line that passes through a given point and is perpendicular to the tangent line at that point.

Formula

The line tangent to the function is given by the following equation

• Definitions
  • is the derivative of at
  • is the point where the line is, this is called the **point of tangency

Example

Given the function find the normal line at .

The function is shown in red, the point on the graph at is shown as a red dot, and the normal line to the function at is shown in blue.