मराठी

Line l is the bisector of an angle ∠A and B is any point on l. BP and BQ are perpendiculars from B to the arms of ∠A (see the given figure). Show that: ΔAPB ≅ ΔAQB - Mathematics

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प्रश्न

Line l is the bisector of an angle ∠A and B is any point on l. BP and BQ are perpendiculars from B to the arms of ∠A (see the given figure). Show that:

  1. ΔAPB ≅ ΔAQB
  2. BP = BQ or B is equidistant from the arms of ∠A.

बेरीज

उत्तर

We have, l is the bisector of ∠QAP.

∴ ∠QAB = ∠PAB

and ∠Q = ∠P       ...[Each 90°]

⇒ ∠ABQ = ∠ABP    ...[By angle sum property of △]

i. Now, in △APB and △AQB, we have

∠ABP = ∠ABQ       ...[Proved above]

AB = BA            ...[Common]

∠PAB ≅ ∠QAB      ...[Given]

△APB ≅ △AQB     ...[By ASA congruency]

ii. Since, △APB ≅ △AQB

⇒ BP =  BQ     ...[By Corresponding parts of congruent triangles]

i.e., [Perpendicular distance of B from AP] = [Perpendicular distance of B from AQ]

Thus, the point B is equidistant from the arms of ∠A.

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Criteria for Congruence of Triangles
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 7: Triangles - Exercise 7.1 [पृष्ठ ११९]

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एनसीईआरटी Mathematics [English] Class 9
पाठ 7 Triangles
Exercise 7.1 | Q 5 | पृष्ठ ११९

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