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Question:

In given figures, sides AB and BC and median AD of a triangle ABC are respectively proportional to sides PQ, QR and median PM of triangle PQR. Show that triangle ABC is similar to triangle PQR.

Solution:

Given AD and PM are medians of triangle ABC and triangle PQR, ∴ BD = 1/2 BC and QM = 1/2 QR (1) Given that, AB/PQ = BC/QR = AD/PM (2) ∴ From (1) and (2), AB/PQ = BD/QM = AD/PM.. (3) In triangle ABD and triangle PQM AB/PQ = BD/QM = AD/PM [From (3)] ∴ By SSS criterian of proportionality triangle ABD is similar to triangle PQM ∴ ∠B = ∠Q (Corresponding Sides of Similar Triangles) (4) In triangle ABC and triangle PQR AB/PQ = BC/QR (From 2) ∠B = ∠Q (From 4) ∴ By SAS criterian of proportionality triangle ABC is similar to triangle PQR [hence proved]