Given AB=OC
From fig, name ptbetween A and O E, so radius: OB=OC=OD=OE=AB
In Tr OAB: AB=OB Let ABO=x, BAo = AOB= y
In Tr OBC, OB=OC, let BCo=CBo=z,
So BOC= 180-2z
Now AOB+BOC+COD = 180 (linear pair)
Using 1, AOB+BOC = 120
=> y+180-2z = 120 => 2z-y = 60 --1
Also, ABO+OBC=180 =>x+z = 180 --2
And, Sum of angle in Tr OAB = 180=> x+2y = 180 --3
Using 1 & 2, 2(x+y) = 320 =>x+y = 160 --4
Using 3 & 4, y=20
So A is suff
Using 2. BOC=100 as OBC=BOC=40 given
=> x= 140
so 2y = 40 => y = 20
So BV is suff.l
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