Ex 11.1, 3
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°