Page 23 - ENGINEERING DRAWING
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Steps of construction:
i. Draw the line Ol
ii. With O as centre draw an arc of any radius to cut the line l at A.
iii. With same radius and with A as centre draw another arc to cut the previous arc
at B.
iv. With B as centre draw another arc of the same radius to cut the first arc at C.
o
v. Join O to C. The angle ∠AOC is 120 .
c) Construct a right angle 90 o
Steps of construction:
o
i. To construct a 90 angle, bisect the straight angle 180 o.
ii. Mark a point O on a straight line l.
iii. With O as centre draw arcs of any radius to cut the line l at A and B.
iv. Now ∠AOB = 180°.
v. With A and B as centres and with the radius more than half of AB draw arcs above
AB to intersect each other at C.
o
vi. Join O to C. The angle ∠AOC is 90 .
