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Contests
National and Regional Contests
USA Contests
MAA AMC
AMC 12/AHSME
1987 AMC 12/AHSME
6
6
Part of
1987 AMC 12/AHSME
Problems
(1)
1987 AMC 12 #6 - Triangle Angle Chasing
Source:
12/31/2011
In the
△
A
B
C
\triangle ABC
△
A
BC
shown,
D
D
D
is some interior point, and
x
,
y
,
z
,
w
x, y, z, w
x
,
y
,
z
,
w
are the measures of angles in degrees. Solve for
x
x
x
in terms of
y
,
z
y, z
y
,
z
and
w
w
w
. [asy] draw((0,0)--(10,0)--(2,7)--cycle); draw((0,0)--(4,3)--(10,0)); label("A", (0,0), SW); label("B", (10,0), SE); label("C", (2,7), W); label("D", (4,3), N); label("x", (2.25,6)); label("y", (1.5,2), SW); label("
z
z
z
", (7.88,1.5)); label("w", (4,2.85), S); [/asy]
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
a
n
>
w
−
y
−
z
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
a
n
>
w
−
2
y
−
2
z
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
a
n
>
180
−
w
−
y
−
z
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
a
n
>
2
w
−
y
−
z
<
s
p
a
n
c
l
a
s
s
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
a
n
>
180
−
w
+
y
+
z
<span class='latex-bold'>(A)</span>\ w-y-z \qquad<span class='latex-bold'>(B)</span>\ w-2y-2z \qquad<span class='latex-bold'>(C)</span>\ 180-w-y-z \\ \qquad<span class='latex-bold'>(D)</span>\ 2w-y-z \qquad<span class='latex-bold'>(E)</span>\ 180-w+y+z
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
A
)
<
/
s
p
an
>
w
−
y
−
z
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
B
)
<
/
s
p
an
>
w
−
2
y
−
2
z
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
C
)
<
/
s
p
an
>
180
−
w
−
y
−
z
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
D
)
<
/
s
p
an
>
2
w
−
y
−
z
<
s
p
an
c
l
a
ss
=
′
l
a
t
e
x
−
b
o
l
d
′
>
(
E
)
<
/
s
p
an
>
180
−
w
+
y
+
z
AMC