NCERT Solutions for Class 9th Maths: Chapter 7 Triangles Exercise 7.2

Discussion in 'CBSE Class 9 Maths Help' started by saralas, May 18, 2014.

  1. saralas

    saralas Member

    In an isosceles triangle ABC, with AB = AC, the bisectors of [​IMG]B and [​IMG]C intersect each other at O. Join A to O. Show that: (i) OB = OC (ii) AO bisects [​IMG]A

    Answer:

    (i) It is given that in triangle ABC, AC = AB
    [​IMG] [​IMG]ACB = [​IMG]ABC (angles opposite to equal sides of a triangle are equal)
    [​IMG][​IMG]
    [​IMG][​IMG]OBC = [​IMG]OBC
    [​IMG]OB = OC (sides opposite to equal angles of a triangle are also equal)

    (ii) Now in [​IMG]OAB and [​IMG]OAC
    AO =AO (common)
    AB = AC (given)
    OB = OC (proved above)
    So, [​IMG]OAB [​IMG] [​IMG]OAC (by SSS congruence rule)
    [​IMG][​IMG]BAO = [​IMG]CAO (C.P.C.T.)

    NCERT Solutions for Class 9th Maths Exercise  7.2 Q1.JPG



  2. saralas

    saralas Member

    In [​IMG]ABC, AD is the perpendicular bisector of BC (see the given figure). Show that [​IMG]ABC is an isosceles triangle in which AB = AC.

    NCERT Solutions for Class 9th Maths Exercise  7.2 Q2.JPG
  3. saralas

    saralas Member

    In [​IMG]ADC and [​IMG]ADB
    AD = AD (Common)
    [​IMG]ADC =[​IMG]ADB (each 90o)
    CD = BD (AD is the perpendicular bisector of BC)

    NCERT Solutions for Class 9th Maths Ex 7.2 Q2.JPG

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