1. Chapter 11 Class 9 Constructions
  2. Concept wise
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Construction 11.3 : To construct an angle of 60 at the initial Point of a given ray. Let us take a ray AB with initial Point A. We want to construct a ray AC such that CAB = 60 Steps of Construction : Taking A as centre and some radius, draw an arc of a circle, which intersects AB at Point D. Taking D as Centre and with the same radius as before, draw an arc intersecting the previously drawn arc at point E. Draw the ray AC Passing through E. Thus, CAB is the required angle of 60 Justification We need to prove CAB = 60 Join DE. Since arc AD = Arc AE and using same radius, we drew arc DE Thus, their radius will be the same AE = AD = DE Therefore, EAD is an equilateral triangle EAD = 60 CAB = 60 . Hence justified

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.