Area calculation for overlapping region

I have three overlapping network in a service area with Radius=600,200 and 200. the networks with Radius 200 are inner networks in the service area of radius 600. I use for loop to input radius , and then calculate area. But I don't know how to calculate

As=A1-(A2+A3). where 

A1=pi*600^2, 
A2=pi*200^2, and 
A3=pi*200^2.

please help me

Answer 1

[Image Analyst]

That's the formula for circumference, not area! You need to square the radius

A1 = pi * 600^2
A2 = pi * 200^2
A3 = pi * 200^2
As = A1 - (A2 + A3)

[Khadija Khan]

yeah sorry pi*Ri^2. i need to evaluate As=A1-(A2+A3)

Answer 2

[Khadija Khan]

My Question is still there. How to calculate As=A1-(A2+A3) like I input R and Calculate A inside loop. But How to Calculate AS using equation As=A1-(A2+A3). how can I take these values of A1,A2 and A3 from loop. Plz help

[Image Analyst]

Just like I showed you in my answer. If you want to save all of them, then give As an index:

As(loopIndex) = A1-(A2+A3);

Answer 3

[Khadija Khan]

Thanks Image Analyst I solved it. Thanks for your help.