Nested Region Inclusions

Problem

Consider the three point sets in the plane

M={(x,y)∣∣x∣+∣y∣<1},M=\{(x,y)\mid |x|+|y|<1\}, N={(x,y)  |  (x−12)2+(y+12)2+(x+12)2+(y−12)2<22},N=\left\{(x,y)\;\middle|\;\sqrt{\left(x-\tfrac 12\right)^2+\left(y+\tfrac 12\right)^2}+\sqrt{\left(x+\tfrac 12\right)^2+\left(y-\tfrac 12\right)^2}<2\sqrt 2\right\}, P={(x,y)∣∣x+y∣<1, ∣x∣<1, ∣y∣<1}.P=\{(x,y)\mid |x+y|<1,\ |x|<1,\ |y|<1\}.

Determine, with proof, the inclusion relationships among MM, NN, PP.

Answer

Solution

Difficulty7/10
TopicsSet Theory, Absolute Value, conic sections, analytic geometry

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