Rajiv Tyagi
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Construct an angle of 45° at the initial point of a given ray and justify the construction.

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NCERT Solutions for Class 9 Maths Chapter 11
Important NCERT Questions
Constructions
NCERT Books for Session 2022-2023
CBSE Board, UP Board and Other state Boards
EXERCISE 11.1
Page No:191
Questions No:2

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  1. Get Hindi Medium and English Medium NCERT Solution for Class 9 Maths to download.
    Please follow the link to visit website for first and second term exams solutions.
    https://www.tiwariacademy.com/ncert-solutions/class-9/maths/chapter-11/

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  2. Steps of construction
    (i) Draw a ray AB at the point A.
    (ii) Taking A as centre and a convenient radius, draw an arc which intersect AB at C.
    (iii) Taking C as centre and with the same radius, draw an arc which intersect the previous arc at D.
    (iv) Similarly, taking D as centre, draw arcs with the same radius, draw an arc which intersects at E.
    (v) taking D and E as centre, draw arcs with equal radius (more than half of DE), Which intersect at F.
    (vi) From the point A, draw a ray AF, which intersects arc DE at G.
    (vii) Taking C and G as centre. Draw arcs with equal radius (more than half of CG), which intersect at H.
    (viii) From the point A, draw a ray of 45°.
    Justification: Join GH and CH.
    In ΔAGH and ΔACH,
    GH = CH [∵ Arcs of equal radii]
    AG = AC [∵ Radii of same circle]
    AH = AH [∵ Common]
    So, ΔAGH ≅ ΔACH [∵ SSS Congruency rule]
    ∠GAH = ∠CAH [∵ CPCT]
    Hence, ∠GAH = ∠CAH = 45°

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