Construction 11.3 - Construct angle 60 degree - Chapter 11 Class 9

Construction 11.3 - Chapter 11 Class 9 Constructions - Part 2

Construction 11.3 - Chapter 11 Class 9 Constructions - Part 3

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Construction 11.3 : To construct an angle of 60° at the initial point of a given ray. Steps of Construction : Draw a ray AB with initial point A 2. Taking A as centre and some radius, draw an arc, which intersects AB at Point D. Construction 11.3 : To construct an angle of 60° at the initial point of a given ray. Steps of Construction : Draw a ray AB with initial point A 2. Taking A as centre and some radius, draw an arc, which intersects AB at Point D. 3. Taking D as Centre and with the same radius as before, draw an arc intersecting the previously drawn arc at point E. 4. Draw the ray AC Passing through E. Thus, ∠CAB = 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 (Radius of equal arcs - By Construction) (All angles of equilateral triangle are 60°)

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo