To fins the equation of a tangent to a curve at a point we have to find the gradient
at that point. If
and
are functions of
we find
and substitute a value for
into this expression. If we have to find the equation of the normal to a curve at a point
we find
If we have the coordinates
or only one of these, we may have to find the value ofby solving one or both of the equations
Example:
Find the equation of the tangent and normal when
When
Equation of tangent:
Equation of normal:
