Draw an angle of 80° with the help of a protractor. Then construct angles of

(i) 40° (ii)160° and (iii) 120°.

Draw a ray AB with initial point A.

Draw an angle of 80° with the help of a protractor.

(i) 40°

Steps of Construction:

(a) Draw an arc of any radius taking B as centre (say). This arc cuts arms BA and BC at E and D, respectively.

(b) Now, taking E and D as centres and with the radius more than 1/2 ED, draw two equal arcs which cut each other at F (say).

(c) Draw the ray BA.

Here, ∠ABF is 40°.

(ii) 160°

Steps of Construction:

(a) Draw an arc of any radius taking B as centre (say). This arc cuts arms BA and BC at E and D, respectively.

(b) We take E as centre and draw an arc with same radius, such that it intersects the arc drawn at a point, say F.

(c) On drawing array BG, we get the required angle of 160° i.e. ∠GBC.

(iii) 120°

Steps of Construction:

(a) Draw an arc of any radius taking A as centre (say). This arc cuts arms BA and AC at E and D, respectively.

(b) Now, taking E and D as centres and with the radius more than 1/2 ED, draw two equal arcs which cut each other at P (say). Draw the ray AP. Here, ∠PAB is 40°.

(c) Taking P and D as centres and with the radius more than 1/2 PD, draw an arc which cuts the previous arc.

Hence, ∠FAB = 120°.