Question

how to bisect angle 120

Answer 1

draw a line AB and from A with any radius make a semi circle and name it as AO
with same radius cut the AO on N



your bisected angel of 120°= 60°
is drawn

Answer 2

first draw a line and name it is a and b on its ends which Centre is a and any radius will cut the line with arc and name it is d now with d Centre with same radii make an Arc and again by putting at point a cut the arc another arc and join the intersecting point with point a and it will be of 60 half of 120.
u can make 120 angle and then can bisect it by keeping needle on arcs of 120 angle and radii more than half and then join the point a with a