Answer 1

modern compiler does not support <iostream. h> (.h) extension so for making program you have to do as below example :-
#include<iostream>
using namespace std;

int main ()
{

float r,a,c;
cout<<"enter radius";
cin>>r;
a=3.14*r*r;
c=2*3.14*r;
cout<<"area="<<a;
cout<<"\ncircumference="<<c;
return 0;
}
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