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Mathematics
Mathematics
Problem
Quadrilateral
A
B
C
D
ABCD
A
B
C
D
is inscribed in a circle with centre
O
O
O
. a. (i) Prove that
∠
A
B
C
+
∠
A
D
C
=
180
∘
\angle ABC + \angle ADC = 180^{\circ}
∠
A
B
C
+
∠
A
D
C
=
18
0
∘
. b. (ii) If
∠
A
B
C
=
73
∘
\angle ABC = 73^{\circ}
∠
A
B
C
=
7
3
∘
, find
∠
A
D
C
\angle ADC
∠
A
D
C
.
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