what is the derivation for the formula of the area of a circle?i would like to know how it is derieved. pl help...

The area of the circle is a function of radius of that
circle.

A(r) = `pi` *r^2

We'll
calculate the derivative of the area, differentiating with respect to
r.

Since `pi` is a constant, we'll differentiate r^2, using
the derivative formula:

(x^n)' =
n*(x^(n-1))*(x)'

(x^n)' =
n*(x^(n-1))*1

(x^n)' =
n*(x^(n-1))

Comapring, we'll
get:

(r^2)' =
2*(r^(2-1))*(r)'

(r^2)' =
2*r

dA/dr = A'(r) = 2`pi` r (circumference of the
circle)

The requested derivative of the area
of circle is dA/dr = A'(r) = 2`pi` r.