Plywood, Circular Holes

A circular piece of plywood has a radius of x inches. Four holes, each having a radius of y inches, are removed from the piece. Write a formula for the area of the remaining wood. (These holes don’t overlap each other at all.) Evaluate your formula if x = 10 inches and y = 2 inches. (Use ≈ 3.14).

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The area of the original plywood is x2.
Each hole has an area y2; there are four of them.
Thus the remaining area is x2 – 4y2.
If x = 10 and y = 2 and we use ≈ 3.14, we get
3.14 (100) – 4(3.14)(4) = 263.76 in2.

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