Lesson #49
Implicit Differentiation




Quote of the Day:
"The arithmetic of life does not always have a logical answer." -- Inshirah Abdur-Rauf

Objectives:
The student will take derivatives of implicitly-defined functions.

The student will learn the definitions of orthogonal and normal to a curve.



1. So far, the functions we have been working with have been explicitly expressed in terms of one variable:

y = f(x)       y = sin(x)       y = 3x-5

We often see relations like these:



We can solve these for y in terms of x.

But there are some equations which we can not solve for y:



These relations are said to be implicitly defined and we can find their derivatives using implicit differentiation.

2. Examples:




3. Define orthogonal curves:
Curves which are perpendicular to each other.

Define Normal to a curve
A normal to a curve is the line perpendicular to the tangent line at that point.

Example:




4. Assignment:
p. 253 (1, 8, 12, 15, 17)
Worksheet on Implicit Differentiation

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Send any comments or questions to: David Pleacher