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°.


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