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NMTC
2017 NMTC Junior
3
Geometry without trigonometry
Geometry without trigonometry
Source: NMTC 2017 Juniors P3
October 28, 2017
geometry
Problem Statement
A
D
C
ADC
A
D
C
and
A
B
C
ABC
A
BC
are triangles such that
A
D
=
D
C
AD=DC
A
D
=
D
C
and
A
C
=
A
B
AC=AB
A
C
=
A
B
. If
∠
C
A
B
=
2
0
∘
\angle CAB=20^{\circ}
∠
C
A
B
=
2
0
∘
and
∠
A
D
C
=
10
0
∘
\angle ADC =100^{\circ}
∠
A
D
C
=
10
0
∘
, without using Trigonometry, prove that
A
B
=
B
C
+
C
D
AB=BC+CD
A
B
=
BC
+
C
D
.
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