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Mathematics
Mathematics
Problem
At a point
O
O
O
, three distinct rays
O
A
,
O
B
,
OA, OB,
O
A
,
O
B
,
and
O
C
OC
O
C
are drawn such that
∠
A
O
B
=
110
∘
\angle AOB=110^{\circ}
∠
A
O
B
=
11
0
∘
and
∠
B
O
C
=
70
∘
\angle BOC=70^{\circ}
∠
B
O
C
=
7
0
∘
. (i) Prove that rays
O
A
OA
O
A
and
O
C
OC
O
C
are collinear. (ii) If
O
D
OD
O
D
is the ray opposite to
O
B
OB
O
B
, calculate the measure of
∠
C
O
D
\angle COD
∠
C
O
D
.
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