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In triangle ABC, AB = 5 cm, BC = 12 cm, and AC = 13 cm. In triangle PQR, PQ = 12 cm, QR = 5 cm, and PR = 13 cm. Which of the following is a correct order of congruency?
Triangle ABC is congruent to Triangle PQR
Triangle ABC is congruent to Triangle QPR
Triangle ABC is congruent to Triangle RQP
Triangle ABC is congruent to Triangle PRQ
Triangle ABC is congruent to Triangle QPR
Given: Triangle ABC has side lengths AB = 5 cm, BC = 12 cm, AC = 13 cm. Triangle PQR has side lengths PQ = 12 cm, QR = 5 cm, PR = 13 cm.
Triangle ABC has side lengths AB = 5 cm, BC = 12 cm, AC = 13 cm. Triangle PQR has side lengths PQ = 12 cm, QR = 5 cm, PR = 13 cm.
SSS┬аCongruence┬аPrinciple:┬аIf┬аthree┬аsides┬аof┬аone┬аtriangle┬аare┬аequal┬аto┬аthree┬аsides┬аof┬аanother┬аtriangle,┬аthe┬аtriangles┬аare┬аcongruent.
Map the sides in order of increasing length: (5, 12, 13). In ABC, the sides are AB=5, BC=12, AC=13. In PQR, the sides are QR=5, PQ=12, PR=13. Matching the corresponding segments (AB=QR, BC=PQ, AC=PR) gives the mapping A-Q, B-R, C-P.
Students often assume the order of letters in the names corresponds directly, i.e., A corresponds to P, B to Q, and C to R, which is false if the side lengths do not match in that order.
Identify side lengths of Triangle ABC
List the side lengths of triangle ABC in increasing order: AB=5, BC=12, AC=13.
Sides┬аof┬а╬ФABC:5,12,13
Identify side lengths of Triangle PQR
List the side lengths of triangle PQR: QR=5, PQ=12, PR=13.
Sides┬аof┬а╬ФPQR:5,12,13
Map corresponding vertices
Match the vertices based on side equality: The side of length 5 is AB in ╬ФABC and QR in ╬ФPQR. The side of length 12 is BC in ╬ФABC and PQ in ╬ФPQR. This implies the correspondence AтЖФQ, BтЖФR, and CтЖФP.
╬ФABCтЙЕ╬ФQRP
Verify against options
The order of vertices that maintains the correspondence is AтЖТQ, BтЖТR, CтЖТP. Thus, ╬ФABCтЙЕ╬ФQRP.
╬ФABCтЙЕ╬ФQRP
B is correct because the correspondence of side lengths AB=QR=5, BC=PQ=12, and AC=PR=13 dictates that the vertices must be ordered as AтЖФQ, BтЖФR, and CтЖФP.
This concept of mapping vertices by corresponding side lengths is identical to identifying transformations in Coordinate Geometry, where mapping (x1тАЛ,y1тАЛ) to (x2тАЛ,y2тАЛ) requires consistent ordering.