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Angle AED = Angle AEC:
Let
x = AC.
... cos
= 90°
8
8
x
The required angle is 20,
cos 20 = 2 cos2 - 1 =
p
128
x2
2.2
AC and we have
-
1
In triangle ABC we find that: BC2 = BA2 + AC2 - 2BA × AC cos (24)
... 225 = 400+x2
128
x
X
—
40
.. x2+40x + 175
Multiply by x: ..x 8.6189
-
2 x 20 x x x
+175 = 0
5120
.3
X
=
0
128
x2
..x3 +40x2 + 175x
-
-1)
5120 =
= 0
8
Φ COS
cos
= 21.845°
X
8.6189
The required angle is:
202 x 21.845 = 43.69°
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