Equations of Tangents and Normals to the Curve y=f(x)

Equations of Tangents and Normals to the Curve y=f(x)

Equations of Tangents to the Curve y=f(x)

  • Tangent to a curve at a point is a straight line that just touches the curve at that point.

  • The slope of the tangent to the curve y=f(x) at a point x=a is given by f’(a), the derivative of f(x) evaluated at x=a.

  • The equation of this tangent line can be found using the point-slope form of the equation of a line, which is given by y - y1 = m(x - x1), where (x1, y1) is a point on the line and m is the slope. In the context of a curve y=f(x), x1=a, y1=f(a), and m=f’(a).

Equations of Normals to the Curve y=f(x)

  • A normal to a curve at a point is a straight line perpendicular to the tangent at that point.

  • The slope of the normal to the curve y=f(x) at a point a is the negative reciprocal of the slope of the tangent at that point, i.e., -1/f’(a).

  • The equation of the normal can also be found using the point-slope form of the equation of a line. For a normal, x1=a, y1=f(a) and m=-1/f’(a).

General Tips

  • It is crucial to find the correct derivative of the function, as it gives the slope of the tangent.

  • The negative reciprocal of the derivative at a given point will provide the slope of the normal.

  • Practice applying the techniques to various functions and values of x to become comfortable with deriving equations of tangents and normals.

  • When checking your work, ensure that the tangent touches the curve at the given point and the normal is perpendicular to the tangent.

  • Don’t forget to give your final answer in the form of an equation i.e., y=mx+c. Use the appropriate details from your workings to replace m, x and c.

By understanding and mastering these concepts, you’ll be able to confidently determine equations of tangents and normals for various functions.