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Problems
Contests
National and Regional Contests
South Africa Contests
South Africa National Olympiad
2001 South africa National Olympiad
1
1
Part of
2001 South africa National Olympiad
Problems
(1)
p/2 < AC + BD < p
Source: South Africa 2001
10/1/2005
A
B
C
D
ABCD
A
BC
D
is a convex quadrilateral with perimeter
p
p
p
. Prove that
1
2
p
<
A
C
+
B
D
<
p
.
\dfrac{1}{2}p < AC + BD < p.
2
1
p
<
A
C
+
B
D
<
p
.
(A polygon is convex if all of its interior angles are less than
18
0
∘
180^\circ
18
0
∘
.)
geometry
perimeter
inequalities
triangle inequality