Answer:
2290 mm² or 2289.94 mm²
Explanation:
The radius of the outer circle is the sum of the inner radius and the width of the shaded area: 12.6 mm +17.2 mm = 29.8 mm.
The shaded area is the difference between the area of the outer circle and the area of the inner circle. The area of either circle is given by the formula ...
A = πr²
so, the area of the ring is ...
A = π(29.8 mm)² -π(12.6 mm)² = π(888.04 mm² -158.76 mm²)
A = 3.14(729.28 mm²) = 2289.9392 mm²
The area is about 2289.94 mm², which rounds to 2290 mm².
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Comment on pi
In the calculation here, we have used the required value of pi. If we use one that is more accurate, we find the area to be about 2291.10 mm².