# What is the derivative of f(x) = #sqrt(9-x^2)+4# considering the fact that the radius and tangent are perpendicular at the point of contact?

##### 1 Answer

Apr 2, 2017

#### Explanation:

f'(x) =

The given function represents a circle of radius 3, centered at (0,4). This can be easily put into standard form as follows:

This equation represents a circle centered at (0,4) with radius 3.

In case of a circle, the radius joining the point of contact of any tangent is always perpendicular to the tangent,