∠ADI = 120°
1. Draw a ray \(\overrightarrow{DA}\).
2. Draw an arc with any radius taking ‘D’ as centre intersecting \(\overrightarrow{DA}\) at X.
3. Now draw two successive arcs from X intersecting the previous arc at Y and Z.
4. Join D and Z and produce DZ to I.
5. Now the angle formed ∠ADI is equal to 120°
