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اوجد  الحل

Rc(x-40)=10-rcx

[Rc(x-40)]^2=(10-rcx)^2

X-40=10^2+(rcx)^2-2×10×rcx

X-40=100+x-20rcx

X-x+20rcx=100+40

20rcx=140

Rcx=140/20

Rcx=7

(Rcx)^2=7^2

X=49

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BE =X

 BF = y

(X+3)(y+4)/2 -3y/2 -4X/2=Xy

Xy +12+3y+4X -3y -4X=2Xy

Xy=12 cm²

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