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 Feb 9, 2019
 #1
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Since these triangles are similar....angle BCA = angle EFD

 

 

And ED = EF....so angle EDF = angle EFD

 

So

 

Angle DEF + Angle EDF + Angle EFD = 180

 

42  + Angle EFD    +  Angle EFD =  180

 

2 *Angle EFD =  180 - 42

 

2 * Angle EFD = 138     divide both sides by 2

 

Angle EFD =  69°   =  Angle BCA

 

 

cool cool  cool

 Feb 9, 2019

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