Consider the following sets. cap u is equal to all triangles cap e is equal to x divides x is in cap u and x is equilateral cap i is equal to x divides x is in cap u and x is isosceles cap s is equal to x divides x is in cap u and x is scalene cap A is equal to x divides x is in cap u and x is acute cap o is equal to x divides x is in cap u and x is obtuse cap r is equal to x divides x is in cap u and x is right Which is a subset of cap i ?
Every equilateral triangle has three equal sides, so it also has at least two equal sides and is therefore isosceles. Thus the set of equilateral triangles is a subset of the set of isosceles triangles. The correct choice is cap e.
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