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Comments 2

Carpeting a Donut

SPOILER AHOY It gets even more intuitive. Drawing the lines connecting the centre of the smaller circle with the middle and either end of the chord, we create a right triangle whose sides are 25/2m, r1, r2. Applying the Pythagorean Theorem: (25/2)^2 = r2^2 - r1^2 The required area is: pir2^2 - pir1^2 = pi(r2^2 - r1^2) = pi(25/2)^2

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Salary

SPOILER ALERT

They could simply put their salaries in a sack and count the sum.

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