Explain ASA, SAS, and SSS triangle congruence criteria from rigid-motion congruence.
Complete a missing proof statement or reason
Problem
Complete the missing statement or reason in this proof step: \(AB=DE\), \(BC=EF\), \(\angle~B=\angle~E\), so \(\triangle~ABC~\cong~\triangle~DEF\) by .
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What this problem is really about
To fill a proof blank, classify each given as a side fact or an angle fact before naming any theorem. Then check the angle’s placement relative to the known sides; only after the evidence forms a valid pattern should you write the congruence statement and the reason that supports it.
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