class 8 math lesson 7 (geometry)
TRANSCRIPT
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c
db
a
DA
EB
F
x
C
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...
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:
, :() () () () ()
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a
bcd x
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c
db
a
DA
EB
F
x
C
: , a, b, c, d ab x
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c
db
a
DA
EB
F
x
C :(1) BE BC=a B (2) BF BA=b AC c d
D (3) A, D C, D , ABCD -
xEBF
ABC
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-.(Extra-)
() 4 . , 3 . , 3.5 . , 4.5 . 60
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() 3 . , 3.5 . , 2.8 . 3 . 45
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. ?2. ?. 45 60
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() 4 . , 3 . , 3.5 . , 4.5. 60