Write a program that calculates the area of a ring if its thickness is t cm, and the diameter of the inner circle is d cm (in pascal).

Program kolco;
t, d, r, S: real;
write (‘Enter the thickness of the ring in cm:’);
readln (t);
write (‘Enter the diameter of the inner circle in cm:’);
readln (d);
r: = t + d; {Calculate the radius of the great circle}
S = pi * r * r-pi * d * d; {Find the area of the ring by subtracting from the area of the great circle of radius r the area of the small circle of radius d}
writeln (‘The area of the ring is equal to’, S); {}
When squaring, you can use the built-in Pascal function: sqr (x).

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