We calculate the area of a circle whose diameter is 8 cm long.
pi = 3.14.
The area of the circle is calculated by the formula S = pi * r ^ 2.
The radius of the circle is unknown, but the diameter of the circle d = 8 cm is known.
From the formula d = 2 * r, we find the radius of the circle by the formula r = d / 2.
Substitute the known values into the formulas and calculate first the radius of the circle, and then the area of the circle.
1) r = d / 2 = 8 cm / 2 = 8/2 cm = 4 cm;
2) S = pi * r ^ 2 = 3.14 * (4 cm) ^ 2 = 3.14 * 16 cm ^ 2 = 50.24 cm ^ 2;
From this, we found that the area of the circle is S = 50.24 cm ^ 2.
Answer: 50.24 cm ^ 2.
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