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  1. Chapter 11 Class 9 Constructions
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Construct the angles of the following measurements : (i) 30° Steps of Construction : Draw ray OA Taking A as centre and some radius, draw an arc of a circle, which intersects OA at Point B. Taking B as Centre and with the same radius as before, draw an arc intersecting the previously drawn arc at point C. Draw the ray AD Passing through C. Thus, ∠ AOD = 60° Now we draw bisector of ∠ AOD Taking C and D as Centre , with radius more than 1/2CD, draw arcs intersecting at E. Join OE Thus, ∠ AOE = 30°   (ii) 221/2° 221/2 = 45/2 So, we make 45° and then make its bisector Steps of construction Draw a ray OA. Taking O as centre and any radius, draw an arc cutting OA at B. Now, taking B as centre and with the same radius as before, draw an arc intersecting the previously drawn arc at point C. With C as centre and the same radius, draw an arc cutting the arc at D. With C and D as centres and radius more than 1/2 CD draw two arcs intersecting at P. Join OP.  Thus, ∠ AOP = 90° Now, take B and Q as centers, and radius greater than 1/2 BQ, draw two arcs intersecting at R. Join OR.  Thus, ∠ AOR = 45 Now, take B and S as centers, and radius greater than 1/2 BS, draw two arcs intersecting at T. Join OT.  Thus, ∠ AOT = 221/2°     (iii) 15° 15°  = 30/2 So, we make bisector of 30° Steps of Construction : Draw ray OA Taking A as centre and some radius, draw an arc of a circle, which intersects OA at Point B. Taking B as Centre and with the same radius as before, draw an arc intersecting the previously drawn arc at point C. Draw the ray AD Passing through C. Thus, ∠ AOD = 60° Taking B and C as Centre , with radius more than 1/2 BC, draw arcs intersecting at E. Join OE Thus, ∠ AOE = 30° Taking B and P as Centre , with radius more than 1/2BP, draw arcs intersecting at F. Join OF Thus, ∠ AOF = 15°

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CA Maninder Singh is a Chartered Accountant for the past 8 years. He provides courses for Practical Accounts, Taxation and Efiling at teachoo.com .
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