What is the missing reason in the proof? Statements Reasons 1. line segment ST is the perpendicular bisector of line segment RV 1. given 2. angle STR and angle STV are right angles. 2. def. of perpendicular bisector 3. line segment RS is congruent to line segment VS 3. ? 4. line segment ST is congruent to line segment ST 4 reflexive property 5. triangle RST is congruent to triangle VST 5. HL theorem

Since ST is the perpendicular bisector of RV, it crosses RV at its midpoint. Therefore, S is equidistant from R and V, so RS is congruent to VS by the perpendicular bisector theorem. This makes choice A the missing reason. The other two sides used in the HL theorem are ST, which is shared by both triangles, and the right angles established in step 2.

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